This is really no different than Reddit. There have always been multiple subreddits for the same topic, with slightly different names. Many were created because the “originals” were found lacking at some point.
There’s nothing wrong with people having multiple options. We may eventually end up in a situation like Reddit where certain magazines/communities of the same topic are more trafficked than others and the less trafficked ones “die”.
I think there’s going to be a kind of lifecycle thing that comes with these things. They’ll sort of naturally sort themselves out. To artificially guide it one way or the other would be to imitate the mistakes of Reddit or past aggregate sites.