The more you try to apply logic to cutie marks the iffier the concept gets. It's a nice symbol for growing up and finding yourself, but the world building about it is odd.
For one thing, people change over time. Imagine getting a tattoo for what you were interested in or good at when you were 12.
The cutie mark skill/interest distinction is probably most well done with Rarity. Her mark is literally gems, and she has a spell for finding them, but she's not a miner or a jeweler. Her true talent is more metaphorical, something like unearthing the beauty of the world and others. She's an artist who uses fabric as her canvas. I remember an interview where Faust said Rarity's original element was inspiration, but it was decided that was too abstract for kids, so they went with generosity instead.
But elsewhere, ponies usually have marks in what they do, whether it's magic, flying, or being a waiter. When ponies magically switch or lose cutie marks they acquire or lose those talents. When Apple Bloom had the cutie pox she gained dozens of new talents.
Thunderlane can cook, but his mark is in flying. Presumably he could never cook as well as a chef pony with a cooking mark, nor would a chef pony ever be able to outfly him. Maybe they should've shown a Wonderbolt who doesn't have a flying mark. But then, what's the point of the mark? Why do ponies have them, but not the other races?
There was also this exchange way back in Boast Busters:
Spike: Twenty-five different kinds of tricks and counting. I thought unicorns were only supposed to have a little magic that matches their special talents!
Twilight Sparkle: True, for ponies whose talents are for things like cooking or singing or math. But what if a unicorn's special talent is magic?
Spike: Like you, Twilight, and you know a ton of magic.
Twilight Sparkle: Oh, Spike, stop. I'm sure there are lots of ponies right here in Ponyville that know just as much magic as me.
Spike: Are you kiddin'? I don't think there's another unicorn in all of Equestria with your kind of ability, Twilight.
Starlight has her kind of abilities, and she doesn't have a mark in cooking either.