Is competitive a good place to learn new heroes for the first time?

When I was playing support, I had a tank who's top 3 heroes were all lvl 10, but the tanks he was playing weren't in his top 3, he kept swapping to a new tank after every few deaths. I could also tell as a tank main he didn't know how to play most of them so he must've been new at most of them. Sadly we did not end up winning

Other times I'll get a lv 1 Widow in comp as well, which normally goes about as well as you'd think.

Is this normal to learn new characters in competitive or am I right to think it's better to use Quick Play to get a handle of a character's mechanics before diving into ranked play?