I think the problem becomes that some people are thinking that once they get 4-5 games in with a hero, they want to try a new one. You can't really do that and get good because learning map awareness and enemy strategy and all that is way too hard to do when you're also learning how to play a new hero. Stick with a base of 3-4 heroes and get REALLY good with those heroes that way you can then learn how to play that base against all the other ones. Once that happens, the transition to play those other heroes later on becomes pretty easy,