The question is valid for sure. I could see dMania being more beneficial to the dev than the STEEM ecosystem. To me it becomes sort of an experiment on interface.
Steepshot, DTube, and DLive are more valid to me. An interesting test for the capability of IPFS.
In the end I feel like some of that stuff can be integrated directly into Steemit. More of a usecase on what works and what doesn't.
Also I feel that Instagram and Snapchat have been able to learn from each other what people like. So I kind of see it like that.