If you don't let Steam run in the background, then of course it's not going to be able to update games in the background. The delay in launching games is thus at least partly self-inflicted. And Steam certainly has justifications other than DRM for being strict about keeping games up to date: any networked game will probably need to match the version of the server, and in general it's good policy for Steam to trust developers have good reasons for pushing out updates.

There are also Steam games that don't use Steam's DRM and can be run without Steam. It's up to the individual game developers whether to include the DRM.