GOG's mission statement is applied very selectively. For a long time they did not support windows 10, and even now it's really spotty. It's frequently on a per-game basis, and sometimes games that used to work, don't anymore.
Yeah but at least you can get the games. On my old MacBook (my only "modern" Mac), Steam auto-updated itself to a version that no longer runs on that machine. If that was my only computer (luckily it's not), I'd not only be completely locked out of the games I already installed, I'd also be unable to install any others -- despite the fact the games run perfectly on the machine. At least on GOG I can just go to the website and download the installers, no matter what [relatively-recent] computer I'm using.
