All of that has in fact nothing to do with Steam.
I think this conversation is going over your head.
What? There is no need to offensively end a discussion like that but if you want to...
You talked about the industry in your post. Steam/Valve is only the distributor. They don't decide or even influence which kinds of games were made (apart from the few they make themselves). That's totally up to the big publishers and not to Steam.
D:OS in fact proved that there is a demand for this kind of old-school isometric party RPG which hasn't be satisfied in the last years. But it's not Steam to blame for that, not at all. Also Steam's DRM policies have little to nothing to do with which games have been made in the past.
I think you're mixing up two distinct issues here...
