Steam In house-streaming with non-steam games?

So I noticed steam in game streaming got updated to Beta and I'm very happy for it now its faster, more responsive and works like a charm on even my old PC with a GT-210 provided my Clint machine has 2x GTX 680 SLI but Browsing through my library I also saw that non-Steam games were also there like the EA games purchased from Origin and also Minecraft I didn't get why? Why is steam allowing us to stream Non-Steam Games? And will it stop doing it once the product reaches final stage(non-beta)?