Today there's an article in a #catalan website about alternatives to mainstream social networks (mentions #mastodon and #diaspora) and their benefits. It claims that many struggle financially (precisely because they don't make money out of user's data) and it considers what could be done to make them more popular: mainly pushing posts to mainstream ones and public sector and organisations leading by example
http://www.vilaweb.cat/noticies/lalternativa-al-model-capitalista-de-les-xarxes-socials/