"We (probably?) wouldn't be able to, say, sell capes or have a map marketplace on minecraft.net that works with Steam customers in a way that keeps Valve happy," he adds. Notch worries that inclusion on Steam would divide the PC/Mac market of Minecraft users, rather than offer more to existing players.
It's not as though there's any animosity though, with Notch kicking off the post by lavishing a paragraph of praise upon "the best digital distribution platform I've ever seen." He also notes that Mojang "are talking to Valve about this" to try and make things work for everyone, but, understandably, "We just don't want to limit what we can do with Minecraft."
[Image credit: Steam forums]