Generally, its because people don’t know its an option, or how to do so. Like, even knowing its a good idea, I have no idea where I’d start looking to buy one and I’m fairly informed around tech.

Thanks for your thorough answer. That was my understanding from the research I was doing as well, but I am probably even less of a lawer and was hoping someone with more experience could check my work.

As I said in the post, I understand the technical side. Its the legal aspect I’m asking about. For example, yes, you can freely download a reuseable launcher from GOG, but as its only granting you a licence to the game, that licence can’t be transfered (without GOG’s permission), resold, ect. and if the licence is revoked, continuing to use the installer would be piracy. I’m asking what happens if any of these stores shut down legally. Would licences be revoked/invalidated, or how would that work?

You’re buying a licence either way. Its not like you can resell your GOG games or anything. If that licence is revoked or invalidated, continuing to play the games is piracy. They say you will have three days to backup your installer, but what happens to the licenses in that case? If they end when GOG or Steam go under, legally, it doesn’t matter what DRM is used.