As said, I understand the concerns @bulleth raises. If Steemit is your main focus, then of course the expandibility - with Steemit as a central hub - will add only more noise and competition.

There's two sides to it though. Maybe even three.

First of all, more noise tends to also lead to more eyeballs. More users is also a higher chance of upvotes. But more than upvotes it can mean profile/brand. Just like any other popular UGC platform Steemit will continue to give new experts a platform they didn't have before. Like LiveJournal, Blogspot, Twitter, Linkedin, etc all did and especially the platform which historically is possibly closest to the Steemit... Squidoo.

Second, we need to remember that, indeed, Steemit is an app built on the Steem blockchain. As such, it's a layer. Whether a central hub or not, it is a layer. That meaning that when discussing whether dMania and other apps are valuable or not, the discussion is bi-fold.

Are you/we talking about the Steem blockchain or Steemit the app?

Lastly, the structure of the Steemit blockchain allows anybody to build an app on it. If people think Steemit has become too noisy or has too little quality [for them] on average... everybody can build their own niche on top of it. Even take with them their SP too. Then of course, the catch 22 kicks in and promotion is needed.

Summarized, I get it. But I see the larger benefit. Please, everybody, please keep building. And while the SMT are good for the broader online community, as a Steemit user, I would prefer everybody to build using Steem. That will bring Steem above $100, very quickly.