LM has the strongest immunity out of all the mains, wind with dance of impetus can remove all debuffs for 1 time (and they can be reapplied ) or have ONLY female 2 ninjas immune for 2 rounds, earth main is even worse where he removes only 1 stack of debuffs and doesn't make anyone immune, firemain only does it for 1 turn and has to be manually applied. Lightning main on the other hand just makes all the sword users immune for 2 rounds not to mention that his calm mind makes him immune for all game (if you can get it off b4 u get disabled).

So i don't see a reason LM should have any more debuff clearing abilities (unless they replace root of warrior altogether)

Who uses root tactic? I don't know if you are being serious or not, but here are a few VERY common teams with root of warrior.
Edo Tensei gnw treasure teams (Kushimaru,jinpachi, etc)
Uchiha teams (Anbu itachi,shisui,susano sasuke)
Classic blitz teams (Asuma WB,Darui,mifune)

I'd argue that skewering and the poison fog wave are rarely ever used on water mains, Heal and shark dominate in most teams.

Yeah my bad 3/4 ninjas in your team will be immune. And for the rest of your sentence you are just proving what I said.