Because Chojuro is a god when used right
I've seen people use him with Water main, Ao, Mei, and Jesus they should all rot in hell.

Admittedly, Chojuro probably is better off in the high tiers where only the paying members can access him.
If you don't have other rares, he ain't that good.
I mean, you could run something standard like lightning, Hinata, Chojuro, Zabuza. That'd be okay I guess.