Hmm. I can see what you're getting at, but I don't entirely agree.
Looking at my facebook newsfeed nowadays, for example, there's an awful lot of sharing going on, but it's not original content - there's very little creation going on. I'm slowly weeding this stuff out because what I really want to see is what my friends and family are saying, or posting, for themselves.
I share photos on Instagram as much for my own benefit as anyone else's. That being said, I have found myself thinking things that essentially boil down to, "This will get a lot of likes," and I'm not sure how I feel about it.
You might be a little cynical with the comment about feigning interest though. I'm sure it's true of some people but I know for myself, if I click 'Like' (and especially if I make a comment), it's because I genuinely do like something.