Madara used rinne-rebirth to become alive again after being in edo-tensei version. And it is clearly stated that alive version is way stronger than edo-tenseid' one. Why didn't hokages use rinne-rebirth to fight in better condition against Obito and Madara in Great Ninja War.
Because the jutsu requires a Rinnegan to use it and there wasn't one available on their side.
It is also unclear whether someone summoned by Edo Tensei could use it on themselves.
Madara had Black Zetsu force Obito to perform the jutsu to revive him.