Blaming 5 other people for not understanding to play around 21 other wildly different heroes isn't flexibility in game design. Your are asking 5 other people to play a fundamentally different game than the one they have learned.

You couldn't "individually experiment" because fundamentally you needed team experimentation; you can't play Reinhardt in isolation, and subjecting your team to experimentation on your own whims leads to toxicity.

I think many people who go down the "I should be able to play what I want and people should adapt to me" don't realize they are being selfish in play style in a game like Overwatch.