Facebook and twitter all share a common aspect: mainstream. Every single person in the world knows what Facebook and Twitter are but hardly any knows what Reddit is. Reddit changed the search function and that factored into what the mods are angry about now. Facebook used to change the layout of the entire site whenever they wanted to and largely got away with it. The major difference is internet culture vs. mainstream culture. Internet culture knows what it wants from their sites and gets really angry when they try to change it. Mainstream couldn't care less. It's possible people could leave Facebook and twitter but not likely.
I agree with you but for the last two years or so Reddit has become mainstream. You are right about mainstream users,they don't really care about censorship and the other problems of reddit.