I don't think the "filter bubble puts artificial divides" that didn't already exist. I also don't think anything gets "put," or that anything is "artificial," or that there are actual "divides," or that there exists a "filter bubble."
Facebook didn't program something called "filter_bubble.php." Facebook uses a privacy-sensitive collaborative filtering approach to selecting newsfeed items for you. If you're describing the consequences of collaborative filtering for the average person as "filter bubble," then you're describing a human condition that an average person is interested in collaboratively-filterable things. There exists a population for whom the newsfeed probably isn't that interesting, and I bet they don't like Netflix, TV networks, organized categories in book stores, newspaper editorials, etc. either. "Filter bubble" is something that happens to people. Like 5 other commenters cover this ground.
I really object to this idea of "artificial." Really concretely, choosing what you read next based on what you liked about what you read before sounds super natural to me, at least for the average person. Again, there are people who look hard for "both sides," and I'm sure they love reading Consumer Reports, CQ Researcher and Wikipedia Talk Pages all day. I just don't know if the minority behavior is the natural one. Notice there's no algorithm involved here. Whether its Facebook's C.F. or whether it's just you choosing what to read based on what you liked about what you read before, you get the same result. So even if you think C.F. (and basically what everyone does) is "artificial," I wouldn't peg it on Facebook.
And puts? Who forces anyone to read anything?
I don't think anyone gets divided. You might mean becoming less uncertain / more committed to your position. But neutrality is just a vote for the status quo—still taking a side. I think you mean political and social divisions, and what you're discovering maybe is that everyone actually has them, you just didn't know what they were until you could read people's Facebook posts.
> a movement could have popped up
Have some perspective. In _your_ bubble, you'll think "movement." But there are like a billion Facebook users. Hardly any of them—maybe 0.01%, or 100,000 people—will have any idea what an "anti-SJW," "safe zone" or whatever actually means. There's no movement.