My understanding is the tools that Steam provides as part of it's developer platform are top notch. And there are a lot of integration points such as cloud save

My understanding is the tools that Steam provides as part of it's developer platform are top notch. And there are a lot of integration points such as cloud saves, social, match making, achievements, store, and so on. There is also a robust CD pipeline. I can easily see this providing value above and beyond most other retailers that would sell video games. For example, Best Buy takes a 30% cut for physical merchandise, without providing any of the above mentioned features.