I think there needs to be an easy mechanism for these various front ends to filter out each other's content, and at some point they should start doing it. Then if you want to participate in STEEM 'Twitter', you download that front end and it's content doesn't clog everyone's feeds. This would reduce visibility overall, but if you are looking to build a bunch of verticals on STEEM and scale them out, that separation needs to come in. Existing apps like Appics and Actifit are good examples.