So.
Necromancy- well, I feel fancy, cause I have heard Brandson's lecture about magic systems.
I think that the biggest issue with the Edo Tensei in cannon, not it's power.. the fact it is boring.
Also, if it is relativly easy to do so, I think every village would have done Edo Tensei.
Realisticly, conservative forces, never managed to stop advancment.
(It's funny to read letters from the 19th century about how trains will ruin society in britian, and you could ctrl c z the wordings and the logic it to manifests against the internet).
So, for one thing, the cost for such game breaking power must be high.
Also, I think if we dare and dissect sub issues then, you can build it as something more grounded. And here, I am openly say I will be mostly inspired from Shaman King, which is manga about Necromancy, and I think it's mostly done right.
So... unlimited chakra? How? Where does it come from? DBz androids has some engine, but chakra is life force. I will argue, that without additional jutsus, Edo Tensei zombies should have 0 chakra- it also means that meta chakra jutsus won' work on them.
But endless stamina is also an amazing thing.
https://youtu.be/wI1exNqKHD8
Where the chakra can come from? Well, the user? Scarfices? Still it will be limited, and you need to find a way to pass the chakra.
Maybe cathing bijuus is essential for such task.
And also.. how many?
100 kage level characters need to get their chakra from somewhere.
Also, their souls/ghosts. Who to say, that it's that easy to get them? Who to say, that the souls haven't passed to a new body?
In One Piece, for example, there is a guy who animate corpses, by putting in them the shadows(which In One Piece, seems to be part of the soul),
And they have the personality and skills of the shadow, but the physical abilities of the corpse.
So, it lead to intresting situations- like, one of the characters is Ok-ish swordman(Brooke), and his shadow stolen to animate legendary dragon cutting Samurai called Ryuma.
They fight, and have similiar style. (Brooke use rapier, but Ryuma has katana, so Brooke has a bit of edge on skill, but Ryuma overwhlem him with his physical abilities.
So, like.. imagine.. Madara died billion years ago, so his soul out of reach. But Itachi died recently, so Itachi in Madara's body.
I think such aproache make it more nuanced, and also complicated.
It also will feel less cheap. No 100 kage level zombies with infinite chakra. Much less, and with degrees of OPness.
Maybe there also religouse factor in the forbidness of necrojutsu- maybe it disturb the Cycle Of Reicarnation or something. As Side effect evil Yokais are created in the mortal realm and stuff like that.