We watch something, think of something, read something.
Then we try it out in practice.
Then we observe or have someone else observe the practice and result.
Then we take suggestions and improvements into account from that observation.
Then we start over at one of the points above.
If you only just repeat the "practice" step you'll get set in your ways, get used to doing the same mistakes all over, etc.
And, of course, "there is no accounting for taste" meaning that some of the aforementioned dimensions are very subjective.
People don't do blind taste tests when they cook. They cook something and compare it to their previous memory. Then they slowly diverge and enter some crazy part of the space where no one should be cooking an ingredient that way. There's no notion of something tasting right on its own. You need to compare it against a better version of that dish.
It's easy for two people to cook exactly the same dish, following the same recipe, both of them to think it came out great, and then when they taste each other's to discover that one is dramatically better.