The the first part of the problem here is that you are again assuming that you can just split heroes into carries and supports and anything that isn't either is the other one. I know it's just for the sake of the argument, but oversimplifying the matter that far doesn't do it any favors. And the other problem is that you're not entirely correct - a lot of heroes in dota actually predate the time when people started speaking of heroes strictly in terms of supports and gankers and carries and whatnot. Those terms are just part of the 'metagame' or whatever. There's only a handful of heroes in dota that really only have one way. Maybe some day people will decide they don't really need anyone to play a hard support but will still find use for Witch Doctor. There's only a handful of heroes in dota that aren't very good unless played in a very specific way, but even some of those heroes can bend into a hybrid role if you push them.