Two points.
1) Yes, as pointed out, Steam is DRM. The point of software is to work, period.
Whatever the purpose of that software, anything that gets in the way of fulfilling that purpose is a problem.
When something which is not a core part of software stops it from working, in any circumstances, legal, illegal, fair, unfair, right, wrong - that something is restricting the very essence of the software. If done accidentally, maybe it's a bug. If done deliberately, it's probably DRM. This is why people call DRM 'defective by design'.
2) Some of the new watermarked 'DRM free' solutions are really worse than the old DRM infested solutions, for the customer.
Before, if you bought a song on iTunes, either it would play if you followed the rules, or it wouldn't if you didn't.
Now, if you buy a song on iTunes it will always play, and copies of it will play, too. That's good right? Yes... unless there's a watermark.
Now if your friend makes a copy... or your sister, or brother... and shares that copy on limewire? Guess what - there's a papertrail, and it stops at your door.
If your laptop gets stolen? If some guy doing tech support for you nicks your MP3 folder whilst he's at it?
Those copies will work for all of those people, and all of the people they share copies with, ad infinitum. But the blame will only land in one place - with the person who acutally paid for the god damn thing.
I'd rather it didn't work than put myself at that kind of risk.