You're free to adopt this cynical and pessimistic outlook if you like but you're going a bit far trying to force it on others. Gawd.
If your argument starts with "how do you know you're not the best in the world unless you try" you fucked up.
The physical (and genetic) demands of athletics aside, we were talking about writing. Just starting on a lark is what worked for Haruki Murakami. Again, it's very unlikely you'll be the next Murakami. But at least you'll improve a lot at something you find interesting! What is the downside here, exactly? Unless you're an opportunity-cost-minimising, industrial-output-maximising kind of person. That's fine, but that's not everyone.
The same pattern holds at the elite levels of most things.
How does it hold for writing?
If you don't have that wisdom, trying to pants something is going to result in writing yourself in circles, contradictions, inconsistencies, incoherence of idea, etc.
I'd go so far as to say that for the vast majority of people, if you don't know what you're going to say when you sit down to write, THAT is your problem. Writing is not thinking, thinking is thinking, and you didn't think. If you're trying to think when you should be writing, that's a process failure. If you're not Stephen King or Dean Koontz, trying to be a pantser with your writing is a huge mistake.
What AI is amazing for is taking a core idea/thesis you provide it, and asking you a ton of questions to extract your knowledge/intent, then crystallizing that into an outline/rough draft.