In any case it's not a huge deal and I agree with everything else you said, but I very much disagree it is the least intrusive. A DRM that activates at install and then never needs to be seen again is the least intrusive, and Steam is not that.
Um that is what steam does for DRM. the rest is a chat client/store. it only activates once you do not need to be online unless you are using steamworks and saving on steam cloud.