This is a an interesting question about how you balance a game. I would assume the debuffs, buffs and stats are put in *gorithm and they are checked out how they work.

If it comes too weak they put something on top, if it comes overpowered than they remove something.

Again back to balance - if they a status irremovable ignitiion it will brake the game or to balance it out they have to make it very weak. Both options won't be better than the current one. I actually use Rinne a lot and try to make the best out of his skill set. 7 or 8 out of 10 times I beat p1 Kakuzu teams. Kushina teams is the opposite. But what I like most is his Y+1 chase. When you scale it in round 2 or 3 it already does more damage than your mystery.