[shmerl]

A significant amount of games on Steam require you to run the client to play them (i.e. no service - no game). Also, you can't use Steam backup tool without being connected to the service (or more exactly, you can't install games from that backup).

While technically, some games which don't require the client to run can be manually copied to back them up, Steam forbids using them in the TOS if you don't have an active account. Now imagine a scenario when you have hundreds (or more) games in your library, and such kind of DRMed service just goes bust. Having no access to all those games would make all the downsides of DRM so much more clear, though it would be quite late already.

Either way, Steam is clearly geared towards DRM approach. In contrast, GOG doesn't require anything like that, and neither enforces anything like that. Once you bought some game, you can back it up all you want and install / play it regardless whether your GOG account continues to exist or not.

[Karunamon]

Actually, offline mode is a thing. You still go through the client, but the service being available is neither here nor there.

However, I find that the client offers enough on its own (the in-game overlay, mostly) that I'm more annoyed when I can't get it to work with a game. I have re purchased games I already owned on physical media and other ways to get the Steam integration (and I'm not alone there).

Steam going bust, in addition to being really unlikely, would be a mild annoyance at best, since bypassing it is a simple matter of replacing a DLL.