I did not know this. I wonder why Frontier changed their model then? They used to allow you to launch without Steam, but last year changed it so you need Steam to play ED. I assumed this was a Steam requirement...Most use Steamworks, because it offers things like achievements, workshop support, multiplayer, voice, etc... as well as a bunch of marketing metrics that the developer then has access to. But as a developer, you don't have to use it in order to publish on the Steam platform if you don't want.