i think kishi knows that the readers wont buy into any more et episodes. undoing the dead demon seal is a pretty epuc triumph for orochimaru and reviving the four hokage is a definitive feat i hope delivers the finality to the et jutsu's use. only the sage or his sons would be worthy candidates for justifiable continued use of et but at that point it upsets so much balance and the manga has been wobbling frequently ever since madara was still just a "mystery coffin'.
if the one ring and its 1-3 tomoe were described as 'the that reflects feelings" then how does that change our understanding of subsequent rings and tomoe? complete formation is 3 rings and 3 tomoe. is each ring a reflection something special within the divine or human condition?
it's interesting that the sharingan may grow potentially to rinnegan but does not go through 2 more rings and 6 more tomoe to get there.
it seems the first generation shinobi undetstood things much differently than naruto's and even the sannin generation.