For-profit companies are driven away from being their "own unique thing" by an urge to capture the audience of their competitors by, basically, being their thing as well. Facebook wants to be Facebook+Twitter, and Twitter wants to be Facebook+Twitter. It's kind of silly.
You know, I used to think (contrary to some) that Facebook and Twitter and the like weren't going to go away—they had achieved such network-effect saturation that people are now completely locked in, in a way they weren't with previous networks. I also thought that, despite "kids these days" preferring services like Instagram or Snapchat at a young age (and HN soothsaying doom for the incumbents as a result), the next generation would all end up "growing up into" Facebook et al when they hit the right age-range to care about keeping in contact with family in college &c.
However, I didn't stop to consider that all these networks are effectively trying to modify their features until they all are basically the same thing—and thus, in est, commodities. Any social network you look at nowadays has:
• a pseudo-timeline of prioritized microblog feeds, with inline image/video posts and comment chains;
• the option to "follow" people (where "friending" people is just mutual "following");
• "liking" posts and copying posts onto your own microblog for your friends+followers to see;
• conversations conducted "in public" by posting back and forth on your own feeds, expecting people to follow both you and the people you talk to to get the whole conversation;
And so forth. It's all the same.
At this point, we need a Trillian/Pidgin for social networks—I actually don't care whether a post comes from Facebook or Twitter or Tumblr or Vine or Instagram or wherever; they're all just gloss on a collection-of-feeds API with a few verbs (like, share, post).
I'm honestly surprised no RSS-reader app has jumped on the "social networks are just RSS-reader-like services with more verbs" idea; it'd be perfect for an app like Reeder that already plugs into a ton of private APIs like Feedly/NewsBlur/etc.