So this isn't that relevant to games released recently because they're somewhat actively maintained. The older the game gets, the more dire the situation is. For example, it is nigh impossible to find Soul Reaver for PC. It's unlisted on Steam and GOG have it as "Coming Soon" with a message about Squenix fixing something. EA is the biggest culprit for straight up abandoning games and leaving no option to get them. The Sims 2 for one.

It's easier to see the issue when you go looking for it

I want to shout out OldGamesDownload for maintaining a repository of abandoned games.

So far it mostly happens to mobile games and stuff like the Oculus, but that's largely I think because the medium enables that kind of intermediary malfeasance or whatever you want to call it.

Until we can own, play, resell, and share our digital games without anyone's permission, it's going to keep getting worse for consumers

I haven't build in a cd drive in my PCs in the last few years. I had a BD drive in-between, but barely used it and it's just sitting on a shelf right now, because I can't be bothered to build it in and so far I haven't missed it. So far all digital stores, be it Steam, gog and even Epic, uplay and Origin have not eaten the games I purchased (and in the case of Epic, claimed).

Only games I can't play are MMO games that died. Which is not exactly a problem of the store front or the plattform.