What killed Reddit wasn't its divisions. It was the admins fostering and encouraging those divisions through censorship and vague yet heavy handed Orwellian policies.

One of the most subtle yet insidious changes I noticed on Reddit was how they implemented comment throttling once your per-sub karma dropped too low. And not only that, they later extended it to comment throttle you in all other subs, even ones you hadn't commented in. That seemed to drastically increase the divides and create more clicky subreddits. Anyone even slightly disagreeing would effectively be banned for 10 minutes, reinforcing the echochamber, making most subs far more angry and aggressive.

Every community large enough will develop factions and divisions. That's human nature. There are so many different people, there's no way they're all going to have a lot in common.

This site, should it be fortunate enough to grow to Reddit's former size, will experience the exact same problems. It's inevitable. I just hope this site has better leadership and remembers where it came from, unlike Reddit.