Asmr is a great way to relax if you can actually feel the tingles the videos are supposed to provide, but not everyone gets them. So obviously to someone who can't it just seems incredibly weird. A good asmr video can send the susceptible into a kind of trance.
It's not sexual. I mean yes, people have made sexual asmr videos, but people sexualise all kinds of things ( ͡° ͜ʖ ͡°). The vast majority of viewers and content creators aren't in that business. It is super intimate though, but in the way that cuddling is intimate.