I forgot to mention, but some Steam games are DRM-free.
http://steam.wikia.com/wiki/List_of_DRM-free_games So you can install them and play without the client.
Jeysie: "I can now install and play it whenever I like without the company coming along and denying me access to my game"
I think this is a little paranoid. Steam does not deny you access more than GOG does. I keep my games on GOG library, i don't download them all and put them on an HDD or something like that and i think i'm not the only one. So, you need GOG website to be functional in order to download your games as much as you need Steam client to be functional.
Now don't get me wrong, i prefer GOG games myself, but mostly because they are patched better. I'm not gonna be hypocrite and choosing not to play some games that i want to play just because GOG does not provide them. This is like those people that refuse to get their kids vaccinated because big companies are earning a lot of money.
GOG can coexist with Steam, there is no need to "boycott" one or another. Not that few people not using a service would matter too much... If you refuse to use Steam because of the client of because you can't be online when you want to play specific games, that's fine, but if you refuse just as an ideology, while you hope that some games from Steam, that you want to play will appear on GOG as free-DRM games, it's pretty hypocritical.