It's why I'm prefer to use GOG if possible, their license terms allow me to install/play game on any computers that I own.
Steam allows you to install and play on as many computers as you want too, but neither allows anyone other than you to play the games, Steam is just the only one actively preventing that by requiring that you use your account and only allowing a single computer to be signed into your account at once, though it is still really easy to get around it by using Steam's offline mode.
I'm probably not going to use Steam, much as it kills me. I really like having Steam as a "backup" of many of my games. When I get things on the Indie bundles I download a full copy for Linux and then use the Steam key for regular play, that way if Steam does something I don't like I still have my own DRM-free copy. I don't entirely understand why we can't do that with PA, it's not like it costs more to copy the game (that's part of the very point of software, any limitation on that is artificial scarcity). Why do I HAVE to choose one or the other? But if for some bizarre reason I HAVE to choose then I'll stick with the Ubernet distribution since it means I'll get a DRM-free copy for Linux, meaning I can fire it up without issue five, ten, or even fifteen years from now.
As for myself, I'll use Steam, though I'd like there to be alternative means to download the game in case something happens to Steam. Which there does seem to be, so that's good.
I will use Uber for the first stages of the alpha, but in the early beta I will move to Steam... I need even more steam games, Gotta catch 'em all!