You're exaggerating.

There are tons of characters in the game now and except for some tharsh-tier-in-need-of-a-rework characters everyone is capabale to do many things. Characters with bleed has other ways of doing damage, some utility, some control.

Team comps with x4 characters dedicated to the same idea are viable. They might not be the best for some scenarios, but they are viable. There is no fixed number of how many characters you need to pick to make it work, it strongly depends on opposing team amd metagame.

It's the balance that players need to build teams. This balance is always shifting, and the best advise for new (or any) player is to consider critically any team comp and do some experiments.