Level 75
Probably because vue is the one most talked about on laracasts. I use fetch js and regular JS myself, but I only do business type apps. I don't even like SPA's.
But everyone is different. There are .net core programmers and java and spring boot programmers who have never heard of inertiajs.
Most of these new age JS frameworks will come and go, mainly because they change so much.
Meaning many times a version 2 won't work with version 1 code.
Some languages have backwards compatibility of many years.