That is about as uneducated a take as one could possibly have.

Keep in mind "isekai" as a genre also exists in western entertainment; A Connecticut Yankee in King Arthur's Court and The Chronicles of Narnia are some prominent and famous examples. Are those specifically for shut-ins and nerds too?

Sorry if I struck a nerve, I was being slightly hyperbolic, but why do you think I'm uneducated? I also should have said I was specifically referring to anime since I think that's what most people think of when they hear "isekai".

When we talk about isekai in modern contexts we do commonly refer to the post 2015 Narou-Isekai where one certainly draws a distinction between isekai before 2015 or after.

The thing about "old" isekai is that they exist more as fantasy stories with specific messages and themes, where Narou-Isekai can be specifically placed in the context of the latest evolution of the Otaku after the failure of sekai-kei and the increasing self-indulgence from CGCDT, Battle-Harems all the way to Isekai.