Well that's because pretty much all of the competition are terrible.
There hasn't really been much innovation in digital market space since the concept arose. Valve started it and a few other companies over the years of tried, including Microsoft and all have failed.
I think valve succeeded because they weren't trying to make a digital market place, it started out as just a distribution platform so not every decision was about how to make the most money out of the customer. You make the money on the games, not the platform and then you build up from there.