Valve is not "engrossed in DRM". They have the most lenient DRM that still qualifies as DRM, and the only objectionable aspect of it is the theoretical inability to install a game without access to the Steam servers. Valve's "DRM" scheme has imposes fewer restrictions on the user than most EULAs, and pretty much never gets in the way of legitimate usage. The fact that they don't want to sell their games without Steam is a business decision that is quite unrelated to the DRM question, and more related to their profit motive and the other services Steam provides that vendors like GoG don't.
What don't you like about Steam's DRM system? Does it in any way inconvenience you or restrict you from doing something reasonable with your purchases? Or are you against it for the mere reason that it's been called DRM? Based on your comments, it sounds like you might be trying to make a principled stand without being fully informed, or else there's some nuance to your principles that isn't yet clear to me.
Offline mode has made me realise just how easily DRM means denying me access to my own computer.
- need to be single-user admin with saved password
- didn't know that before? tough! you're locked out from all games including DRM-free ones
- happened again and still can't get offline mode? tough!
- support limits how big a message you can send so I couldn't send complete info (not that they looked)
- support promotes racial hatred, closing issue with poor English and telling me I didn't do what I did.
- follow up support also closed.
- considered small claims court but was convinced it really wasn't worth it.
lesson learned: There is no such thing as "friendly" DRM. When the system decides you are wrong, there is no recourse
 Unless you're a famous blogger, have a personal contact or other out-of-band means unavailable to the masses.
I don't think any clients from Steam or other distributors need to run in order to install or play some game. And as the other commenter pointed out - you don't want suddenly to lose your whole collection if Steam terminates your account.