Twilight Sparkle: Though I am a little stumped. Do the rest of you have any ideas?
DM: Ah, the "phone a friend" option.
Rainbow Dash: Heck if I know. It's all Greek to me.
Pinkie Pie: I don't have a clue either! But I believe in the rest of you!
Fluttershy: Um, this is more of a hunch than an idea, but... "A mark of one's destiny..." Isn't "mark" kind of a specific word choice? I feel like that means it has something to do with our Cutie Marks.
Applejack: Huh... Come to think of it, that's one part of this setting we haven't really interrogated much. Feels like we've just kinda taken it for granted as a "magical pony" kinda thing.
DM: Because it very much is, to be fair.
Rarity: We do get a "special talent" from them... But it's not far-fetched to presume they have some greater magical significance.
Twilight Sparkle: Are Cutie Marks predestined...? Gee, sounds like we're poised to ask deep questions about this fictional world. Wonder why that is.
DM: Oh no, not questions about my painstakingly crafted lore! *Aaaaaanything* but that!
On one hoof, it seem everypony has some kind of farseeing sense to name their children in a way that will fit their cutie mark. On the other hoof, the Cutie Mark Crusaders proved that theory wrong and it was well-established in the show that you can't get a cutie mark that wont feel like its part of yourself, unless you use magic (looking at you Applebloom).
The apparent link between names and cutie marks might well be reflective that talents run in families. Name a foal according to the types of cutie marks that normally run in the family, and there's probably a good chance it'll be compatible with the mark they receive.
Mind you, the accuracy does seem to vary. Among the Mane 6, for instance, Pinkie is named more for her colour, and Rarity's name doesn't seem to link her to a specific mark. It's also possible that the magic that assigns marks takes names into account - for instance, Fluttershy was probably always going to get an animal-related mark, but her name might have been the reason she received butterflies rather than, say, something bear-themed.
What if it's a self-fulfilling kind of prophesy? You name your child Star Gazer or Apple Bottoms and they just get into subjects related to their names because of curiosity, and then poof, cutie mark in astronomy or apple farming.
To be fair, the show did address that not all ponies keep their names as they age. Mrs. Cake used to be "Chiffon Swirl", Pear Butter eventually went by only "Buttercup" and so on.
In Pinkie's case, the shock of bright pink and highly "poofy" mane/tail may have affected her naming. The rest tending to have colors appropriate to rocks and minerals (yes, there are pinkish gemstones, but that family seems more into construction materials -- limestone, quartz, marble... Though Maud is another exception; really -- Maud Pie is practically a human name!)
Worth noting that the Pie family has some 'old fashioned' names. Pinkie's name is Pinkamina Diane Pie. Maud's full name is Maudeleena Daisy Pie, apparently. However their parents are Igneous Rock and Cloudy Quartz, so there's presumably a 'Legal Name' and 'What everyone calls you' name?
You can always take the interpretation (literally) that we're seeing the names as translated from Equine.
My pet theory is that names we are given in the show are non-diegetic. Real pony names are completely different and can only be pronounced by equine vocal tracts. Since the story is targeting a mostly human demographic, the narrator had to come up with English pseudonyms for all the characters.
This theory predicts that a pony's English name is likely to match their job/cutie mark if they first appeared in the show as an adult, but is unlikely to match their future job/cutie mark if they were introduced as a foal.
Unfortunately this theory is contradicted by Open Skies, Clear Skies, and Fluffy Clouds in S5E5.
The name-mark connection started more as a case of the fandom naming background ponies after the few distinguishing factors we had to work with. On a Watsonian level, we have a canon case of a pony changing her name after getting her mark in Mrs. Cake nee Chiffon Swirl. (She may have changed it after marriage, but that doesn't explain changing her first name to Cup.)
Marks do seem to be the physical representation of a self-definining epiphany than predestined pictographic true names, though there is evidence for both. It's all a bit chicken-and-egg. Does discovering a talent give form to the mark, or does the nascent mark provide the talent? Starlight's magical blasphemy certainly doesn't help matters.
This is still one of the most fascinating parts of the setting. Looking forward to seeing how the GM handles it.
A situation where the players HAVE to ask for exposition about the setting to solve the puzzle? Devious! But you know some of us actually do enjoy the lore and exposition enough to ask without being prompted.
In the show, the mane six are shown preforming tasks/jobs that they have no experience or skill in doing and would probably never have been attempting in any other circumstance, specifically because their cutie marks had been switched and they seemed to think they had to, almost as if the cutie marks had some sort of compulsive effect to them. But that sort of thing, being forced to roleplay your character in a certain way, was one of the major issues back in the the Discord debacle, and is something the GM is specifically trying to avoid at this point. Which makes me very interested to see how this played out.
I think it was more the "forced" and "sudden surprise" aspect of playing the characters specifically against what they had been doing. This was discussed and planned with the group, and it's possible they'll be repeating a similar idea by swapping the cutie marks as the basis. Except, since it was discussed among the group ahead of time (even if the details might not have been brought up, to keep some surprise to it), it's going to be handled completely differently. The disparity between "nearly ruining a group" and "the group having fun" with what amounts to "practically the same idea" would lead into the discussion and explanation naturally. The point of them returning to Discord and resolving it with what they planned (the details of which were off-panel) was because they don't want to hurt anyone's feelings but still want to make it clear that it's "their" game and not "one person's" game; it's a game where GM and Players work together for fun even with some conflict between them, not a game where GM and Players are actively trying to upend each other's plans and "win" by dominating and crushing the other side. (For this group, at least.)
As I tend to DM via constantly pulling things from betwixt mine buttocks, I have gotten extremely adept at describing things via stream of consciousness, following a vague notion, and rapidly describing stuff, and changin it as I go... Editing things I've mused too much, adding any odd detail that pops into my head, and sometimes Google some art some random made and describe it best I can when I am REALLY stuck...
This goes for lore too, I t d to leave everything with a thousand loose threads that I can connect at a later date... Or steal a players theory if it's better then what I got!
As a life-long sufferer of ADHD, thinking on the fly and not stop comes easier to me then it does for most, to the point I have DM'd nearly every day for Years now(I have no life, and I like it that way... Because I also got severe stress issues... It's a horrid combo), while on the flip side I do not "prepare" well, and am liable to forget or discard everything I prepared in exchange for a fresh idea I just laid like a fucking golden egg.
Or one I stole from a PC's theory rafting.
My players do not suspect I am literally improvising every single session, and they think my worlds abnormally fleshed out, even tho it really isn't... If they ask for lore, however, I can give them Pages and Pages of the stuff.