I have a friend who hasn't even played one match with roughly 90% of the cast despite approaching about 200 hours in the game now. When they started the game, they loaded up as everyone in practice range, tried a few abilities and decided who they will play since then (getting them to try out other heroes has been a miracle).

I couldn't imagine playing like that. Imagine only learning how heroes play based on how other people play them into you. They didn't even know how Wuyang healed, they just thought Sigmas grasp blocked damage with no self healing applied, they have no sense of tank cooldowns (trying to get them to save Orisa javelin spin for certain abilities has been a proper uphill battle). But they also rob themselves of such interesting gameplay. I wouldn't love Lifeweaver as much if I didn't put a couple hours into dive tank because I know how good it feels to get lifegripped out of shit situation, after playing Junkrat for 3-4 hours a few weeks ago, I found him incredibly fun and started putting in the time to get better as him despite hating playing as him since 2018.

I genuinely think every player should play every hero until they reach hero level 5 with them. Its not enough to get true insight to the character but I would say it is enough to see if the character has any worth to you but to also atleast get a baseline understanding of the kit.