We don't allow them to be listed in our store due to the extreme load they created on servers and also due to the content restrictions that some countries had established. This created a huge liability for site owners as Australia (IIRC) and a few others decided that all content producers need to be paid when their work appeared on other sites. Google is fighting the law though so it may get reversed or at least hopefully updated so that people can still grab content with attribution. The main reason we pulled them was the extreme load as they crashed servers.

I believe both SocialApps.Tech and SocialNetworking.Solutions have rss importers on their own listings.