Point of order: Reincarnation, especially how it's commonly used in Anime, falls under the Isekai banner regardless of where the MC is reincarnated to or from.

And that's a great deal of the pointlessness of Isekai. If someone being reincarnated or being brought from another world doesn't change the story for better or worse... why is it necessary?

"I was a salaryman in Toky-" Just start out as a kid living on a farm!

"We have to summon the Great Heroe-" Start the Anime from the Priests' perspective and don't even say where the Heroes came from!