Self-organization, limited time and cognition causes these bubbles. Wrote about this back as one of my papers back in 2003/2004, can't remember. (been happening since early internet bboards) Algorithms, if profit driven are just making it "worse". Imo, my approach is - the world's too damn messy for sustained control. So might be intentional, but most likely it wouldn't go "according to plan" after some time.
Edit: but the paper i wrote was more about Human Behaviours in Virtual Space (on the Internet) . Big data and stuff weren't big back then, but people were experimenting and communicating, hence why there are splinters, it's bound to happen (can't imagine an internet without its little pockets of chatrooms, forums, groups, etc).
Thinking about it now, my paper is probably already obsolete. Data sciences and blockchains are certainly changing up the scene.
Yeah. Facebook were really the pioneers of this sort of thing, and with all the psychological experiments they have conducted on their users since its conception, it's very difficult to believe that they are not aware of the division that their algorithms are causing.
I'd have to say I'm leaning towards it being a deliberate wedge driven between the people. Understandable too, because they day we surpass our petty labeling of ourselves and others and truly begin to unite, is the day that we start to make changes in the world that the people currently running it do not want to see.