It's a little different. Reddit doesn't choose the content presented to users, they allow the community to self-sort into community-managed subreddits with the

It's a little different. Reddit doesn't choose the content presented to users, they allow the community to self-sort into community-managed subreddits with their own cultures and preferences and voting behavior. In fact reddit only barely exerts any control over the selection of subreddit moderators (mostly stepping in only to resolve things in extremis). Facebook's algorithms decide on everything in your feed. If you aren't interested in politics on reddit you might never see it at all. If Facebook thinks you might be a republican (and often that's just a demographic thing coupled with a few past clicks on political stories), they will literally fill your screen with paid advertising designed to drive your political preferences. The point is that division is visible on Reddit (and everywhere), but driven and encouraged by Facebook. And that these are different phenomena. I'm not completely sure I agree, but the point isn't as simple as "division exists".