I don't know if I'm "hip" enough to any of the "cool" terms being used these days, but I believe FWB may have gone the way of the dinosaurs by now. It's been at least ten years since it was first used, right? Many fad terms like that dissipate after a run of a few years, so by their ten-year mark, they're ancient.
Regardless of whether or not it's still called that, I think it counts as a type of relationship.
It's still in use and is the anti-relationship. People who genuinely want that situation don't generally want to be actual friends, either. They want a regular sex partner without all the trappings of a relationship. Even being friends- going places and doing non-sexual things with someone, usually results in feelings and obligations. So, it's more about having regular "benefits" without anything else. If you actually are "friends," and look after each other like friends should do, then it is a relationship, no matter what label you put on it.
My last gf and I (about 18 years ago) decided to to be just f*** buddies. We still went places and did stuff, but all we really wanted is for the day to end, so we could carouse.
It seems he's saying two different things; that they were each in it just for the sex, and that in the evenings they just wanted to club-crawl. *Shrug.
Don't know. I've never used it and never heard it until perhaps 20 years ago or even more recently. In my day we just called it having sex with a friend. Yes it is a relationship of sorts but the way young people seem to use it is as a kind of trial relationship. Like they are hesitant about getting involved as deeply as boyfriend and girlfriend and are more testing the waters. That is my observation. They used to talk about that a lot on answerbag a few years ago.
People said "friends with benefits" when I was in college from 2010-2014, so I don't think it's entirely fallen out of usage. None of the FWB "relationships" I knew of lasted very long, though. Someone always wants more.