I became a captain on a Dash 8 at age 25 after flying airline turboprops for 2200hours and GA airplanes for another couple of hundred. I am doubtless a better captain now after 10+ years on the left seat but I am convinced that I was a good captain even then.
I have flown with many 200hr copilots ever since and found that a lot more depends on training and proper selection than overall experience. I have flown with very few copilots with more than 3000hrs as ours usually get upgraded by then. Those I met were mostly very good though that doesn't mean those with fewer hours didn't cut the mustard.
More experience is good but I don't think that 10 years of experience can reasonably be mandated for captains.