The last time I played retail WoW in late Legion there were pug groups doing mythic for earlier tiers. Usually you would get a couple bosses down. I know, you have a bit better gear, but its not a whole new expansion worth of +level and gear, and its the most random of pugs, whoever was in lfg at that moment.
If you came to these forums at that time, Nost being closed and Blizz announcing Classic dominated the discussion. I remember all these arguments about how much more difficult the game is for "modern gamers" (whatever that means) and how easy vanilla WoW raids were. Still don't get it. Granted I haven't seriously raided in a decade but I have bounced into the game casually a couple times. I don't see any real evidence the game has entered some totally different stratosphere.
The truth is there is nothing that that difficult about WoW raiding. Its not LoL, its not CS, or any of the many fps games that draw a huge competitive audience. Its designed so the few thousand or so raiders that actually put in all the out of raid work required can complete it within a few months. Which regularly happens like clockwork these days. When was the last time the whole of the raiding community was stuck on an encounter like it was with alone in the dark? That tells you Blizz really hasn't pushed difficulty like they used to.