I think you are overlooking the fact that people upgrade their computers, reinstall the OS, have hard drive failures/fires/floods. I myself have lost many save games because when I reinstalled Windows I forgot to backup the old games which save in their program files folder instead of the my documents folder.
Games that are long enough to need saves and that have enough replay value for that to come up as an issue are sadly few and far between these days. The only time I've ever ran into something like that in the remotely near past was after getting a sequel that had an import for the previous game which had been released four years prior... which wasn't really a major loss at all (you can generally download other people's saves that are similar enough to hit all the flags they check in those sorts of cases).
But it's social features are non-existant, it's got no way to invite a friend into a game I'm already playing, it doesn't have stuff like cloud saves or achievements, doesn't have any way to enable auto-patching, and the game selection isn't even close.
Social features and achievements are not a value-add for everyone, and auto patching only really matters for frequently updated multiplayer games (it's actually an added barrier for single-player games, where it may not affect anything you care about but you still have to download it to play anyway).
As for selection, all that matters is that they have what you want (which basically just means new releases).
