Tangential isekai. These are the time skip, reincarnated, or other ‘from this world but not’ types
Writing crutch to explain a world with ‘game-like’ qualities.
Nearly all Isekai currently out do not need to be isekai, it’s just being overused to quickly explain why/how the world and MC are so different from baseline reality. Usually the real point is to connect the character to a more understandable and relatable base.
I’ve been reading way too many light novels lately, and many of them are labeled isekai, but it’s completely inconsequential outside of a very minor plot point.