I think you're on the right track, thinking of selection effects. I don't think the effect you mentioned explains why to expect something requiring very nearly 10k hours, even though there's some obvious truth to it. I take it you'd put a wide deviation around the (central?) 10k figure.

Yes, I would. I'm not deeply invested in the correctness of my exact explanation; I'd find explanations similar to it as plausible. It's just the idea that came to mind when I actually queried my brain for the answer your original question.