[LunaSea]

Reddit and Hacker News are rather content aggregators rather than social networks. Google+ and Twitter have the same issues than Facebook on these specific issues. LinkedIn is a bit too specialised for professional messages and they too like Google+ and Twitter don't have a great track record concerning privacy and abusing their position.

[bashinator]

Reddit may have started as a content aggregator, but there are plenty of subs that mostly or only have original/self-posted content. talesfrom*, various hobby groups, support groups, crowd-sourced advice columns like legaladvice or relationships.

It's well past being solely an aggregator.