None of them were Sage of the 6 path for even a few seconds and had Kamui to top.
Obito stated OUR chakras are connected to the living world, meaning both him and Rin, their chakras form a bridge that connects them, Kamui is not needed, that's just how Obito chose to transverse to save time, as Rin told him to "Hurry up."
Hasn't chakra and powers lingered before?
Dead Minato and Kushihna left his chakra to do the "talk" or help fighting Kurama.
That's completely different than this case. The Minato and Kushina we saw in Naruto were chakra manisfestations meant to emulate them, but had no connection with them in the afterlife, as Minato couldn't recall Naruto learning Sage Mode upon arriving back to the living world, or his meeting with Naruto.
Sage Hogomoro is just floating around somehow even after his death ( beasts said he separate them before death and died). Gives chakra and powers to both Naruto and Sasuke. (How much he had initially?)
Indra and Ashura are transmigrating.
These are good points on it happening before, I'll give you that.
Dan went to visit Tsunade and gave rest of his chakra to Tusnade before disappearing again. (chakra transfer from spirit)
Once again, completely different scenario. Regardless of being alive or dead, Dan had a special technique that allowed him to control his soul. Dan visited Tsunade BEFORE he went to the afterlife, before he left the impure world. These two facts mean this can't be applied to this situation.
Gara was able to be revived by some jutsu and can also use sand now on seemingly greater level(?? but yea) without Shukaku.
Different as well, Chiyo transferred he life force into him so he can be brought back to life while she was still alive and in the impure world, she didn't cross any boundaries.
Kinkaku and ginkaku using Kurama 's chakra for it got ingrained with the contact they had for short period.
What?
It's not like first time it happened.
Susano requirements got corrected when Madara used it while blind. Unless story ends one can only speculate abilities and writers fix it as they need to.
This is one of many retcons Kishi has made to the story. While the use of retcons isn't bad, Kishi has overused them, and that's why this is no excuse. If retcons were alcohol, Naruto would be in the ICU for liver failure and severe alcohol poisoning.
Now you may not like the development or how he used his options and all that but at least stop spamming the same thread topic you guys. -_-