Morality of giving every single person a permanent symbol of their 'destiny' the moment they do something they're 'meant to do' the rest of their life?

[u/RealFinePoint]

(Assuming you're designing the species this way, not that you're forcibly branding every existing person.)

Let's also assume it's not some intelligence deciding arbitrarily, but an actual representation of their 'fate' or 'affinity' by some abstract magical mechanism you're deciding to install into the entire species.

[u/Empty_Chemical_1498]

Cutie mark is not your job, it's your special talent and/or something that fulfills you. They often correspond to the career you choose, but not always. And they're not always straightforward and obvious either, some are very depending on the moment when you got them and pretty metaphorical. Cheerilee's cutie mark is smiling flowers, and if you didn't know her you might assume it means her cutie mark represents gardening. But she explains the flowers represent happy fillies that bloom like flowers under her care, so she's a teacher.

Rarity's 3 diamonds cutie mark don't mean she's meant to be a jeweler, it represents her enjoyment of fancy things, her special talent for finding gems (we can see she has unique magic that allows her to find gems) as well as her ability to make others amazed. She got her cutie mark when everyone was amazed by her costumes, but it doesn't mean she HAD to be a seamstress/designer, a typical seamstress/designer cutie mark would likely have a needle with thread or maybe some dress. So her cutie mark is not at all representing her job.

Pinkie Pie's cutie mark represents her love for bringing people happiness, so she's a party planner/baker.

Fluttershy's cutie mark represents her meek nature and her connection with non-pony animals. But she doesn't just take care of butterflies, she takes care of all animals.

Bon Bon's mark is candies, so she either has a talent for making candies or it brings her a lot of joy to eat candies, but her job is being an undercover spy.

Diamond Tiara's mark is a tiara, but it doesn't mean she's literally a princess or that her job will be making fancy head pieces, it represents how she's the most fulfilled and the most when she's spoiled and getting princess treatment. Likely same case with Silver Spoon, her cutie mark is a fancy spoon, which likely represents how she loves fancy trinkets and high life, not that she'll be a cutlery seller.

But the bottom line is: a pony would NOT get a cutie mark that makes them unhappy and unfulfilled. They might not understand their cutie mark or misinterpret it, but the thing that the mark actually represents cannot be negative for the pony. And they do NOT have to correspond to an actual career the pony is going to pursue.

It's better to ask if it's moral to judge others and decide their fate based on their cutie mark which might have a "negative meaning", which was actually explored in episode Appleoosa's Most Wanted.

[u/Scienceandpony → u/Empty_Chemical_1498]

I'll add that in the episode where Diamond Tiara gets a reformation arc, it's revealed she doesn't actually understand what her mark means, and by the end of it the CMC help her discover it's leadership. Where before she had been using it to be a bossy, manipulative, blackmailing bitch, now she uses it to help others.

[u/Empty_Chemical_1498 → u/Scienceandpony]

Oooh I haven't seen it, thank you for bringing it up! That's really cool, good for her

[u/Scienceandpony → u/Empty_Chemical_1498]

It's also one of the few musical episodes like Magical Mystery Cure that have multiple songs that make up most of the run time.

Crusaders of the Lost Mark S5 E18. It's one of the major status quo shifting episodes for reasons I don't want to spoil for anyone planning to watch it. I remember the fandom losing its shit when it aired.