If I understand the term Isekai correctly, it's where the protagonist becomes trapped in an alternate world or reality, fictitious or not, correct?
I think that a well written Isekai that would cause as much immersion as possible is an ideal escape from the horrors currently happening in the real world. You can become that character, play around, explore, experiment in a safe place.
After all, the reason why most people enjoy books, movies, even television shows, is to escape reality for a little while. It's a rest stop. The Isekai simply allows a front row seat as the main character exploring this escapism.
It's also a reason why many people enjoy table top role playing games and video games. I get to be somebody somewhere other than who I am right here.