Amaterasu isn't even that great.

[Xāvî1]

Did it kill anyone yet NO! SO its not a great jutsu! No wonder madara doesn't like using it either!

 

[UltimateDeadpool]

Edo tensei could'nt die from regular attacks anyway, the only way to defeat them, was to make them have no regret's, basically in a way "Talk no justu", so if Nagato was alive, The amatarasu would have had affect on him, but like you said either way it wouldn't help because edo's can't kill edo's

Amaterasu should still burn them, and it should stop them from regenerating so long as it's burning. Afterall, if you put a new log in a fire, will it not burn too?

Amaterasu did also succeed in burning the joint of Nagato's elbow, after a long conversation between Itachi, Naruto, and Bee, and didn't seem to really do any other damage despite being on a large section of his body.

Rinnegan can't sense chakra build up

Nagato has chakra sensing.

 

[AlphaScythian]

if for some reason amaterasu isnt effective then you're not using enough of it.
Only couple of characters can completely negate it and all are god tiers others either lucky either temporary solution and wont survive another shot.

i myself wouldnt mind having ability to set shit on inextinfuishable fire for 7 days at sight but yeah you'r probably right its not THAT great

 

[Observer]

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