LoL and WoW basically work perfectly on Linux (platinum rated). As for BG3, it works fine for the most part with Proton-GE / Proton Experimental. But since it’s still very new though, expect bugs, but also expect the compatibility to get even better within the next few weeks.
My question then is “Well, do you game?”
Really though, the question shouldn’t be “do you game”, but "do you like tinkering around, fixing things, troubleshooting, and learning new things, in your free time? ", or, “do you like major changes, and having the patience to make a major change in your life work, or would you rather prefer familiarity and stability, a mindset of ‘if it ain’t broke, don’t fix it’?”
If someone has been running Windows for 35 years and hasn’t checked out Linux already in some capacity, I doubt they’re the kind who likes change, the kind of person who likes to experiment and tinker. Personally, I wouldn’t recommend Linux to them based on that reason, unless they’re also the non-tech-savvy kind who have very simple requirements - like my Mum and Dad, who’ve been running Linux for over a decade now without any issues (because their requirements are very simple, so Linux fits their needs perfectly).