Is there a reason for non-console players to even buy in DVD form anymore, instead of Steam or similar markets? I mean, I get that if you live in Canada or Australia your bandwidth sucks and you have caps, but for most cases download speeds are way faster than DVD shipping speeds.
I've heard a few people express concerns around whether they actually own Steam games, and whether those games might suddenly be pulled or otherwise made unavailable without the courtesy of a purchase price refund. I'm not entirely unsympathetic, but on the other hand, to the best of my knowledge that's never actually happened, so...
There's also the possibility of bugs or other errors causing items to disappear from the library. Searching around, it sounds like it's happened to a few people.