I think we're getting sidetracked on the DRM vs Copy-protection argument. Many people (and I'm guilty of this, too) are using the term DRM interchangeably with copy protection. Yes, Steam is technically DRM. Just as GoG's downloader is DRM, and their login service on their page is DRM.
No. You are mixing two unrelated subjects which I admit are easy to mix.
Let's clarify.
Firstly, there is authentication. I.e. a method to prove that you are you. That's the log-in service which authenticates you when you buy something in order to prevent strangers from buying stuff on your account and in order to attribute your purchases to you. That's completely fine, totally reasonable and it has nothing to do with DRM. Authentication happens at the purchase time. It's not any different than coming personally to the store and paying money. Your presence in the store authenticates that you are making the purchase.
Then there can be DRM. DRM doesn't just want a proof that you are you. Even if it knows that you are you, DRM
restricts what you can do with your product. Note the difference. That's already not fine at all, because in order to implement such restrictions DRM treats you like a criminal.
So let's reiterate - authentication for purchasing is completely fine. DRM is unacceptable.
DRM simply means "Digital Rights Management"
What DRM really means (i.e. in essence) is Digital Restrictions Management. DRM attempts to control your system and restrict the way you can use your purchased product. I.e. well after you already bought it.
I can copy any of those games to another computer that doesn't have Steam on it or an internet connection and they will run. Does that still mean they have DRM because they came from Steam?
That's a "poor man" form of being DRM-free? Valve aren't some amateur company. In order to make DRM-free offerings their games have to be downloadable as explicit packages without some "copy that directory and you have a chance it won't choke if you run it elsewhere without a Steam client". That's not normal - that's like dancing around a service which doesn't attempt to be DRM-free. Even their official backup tool (which Seam offers) can't reinstall the backup without their own client and connecting to your Steam account. That's not DRM-free in my view at all.
