HexaNoid

Well, look at Kaqn for instance. In many vids he has used Tsubaki, Hakumen, Ragna and Jin, and he's still good. There is also another player called Shadow2bolt. He uses like half the cast and he's really good. Picking up more characters just helps you to get a better understanding of how the character could/should be played and you'll know what to expect when playing against them. You'll know what to punish and what to be aware of. Having said that, I was actually considering of picking up Platinum and Mu-12 but I think I have my limits.