I mean yes but remember the target audience, the target audience is in Japan and many of the Japanese people are kinda depressed if not borderline suicidal, isekai is basically a way to flee reality. This goes for the authors and the audience alike, they really don’t like our world.

For the same world reincarnation thats usually a bigger plot point and has more meaning.

For the very rare case of fantasy world to fantasy world… Thats either completely irrelevant or very very relevant, no in-between, wich is funny.