There are some games that just will not work even under proton, or that have functional restrictions. It's way fewer games than it used to be, but it's still not an absolutely perfect solution. I would love to make Linux my gaming OS instead of my "getting shit done" OS like it currently is, I've been advocating for it for a few decades at this point and it's almost there, but it's not to a point yet where I can unreservedly recommend it to gamers. If you aren't a gamer I'd say it's already good enough for anything you need.