BU crew could never really split-off. I'm not sure why the bitcoin core reddit people kept circulating that. A) If they tried it, their difficulties would be so bad for both sides, without an additional fork to the network, that they couldn't properly handle transactions for a time frame. OR they would just spike fees. $10 bitcoin transactions or something. B) BU crew if they just made another altcoin, it wouldn't be profitable to mine, so they would switch back to mining bitcoin anyway... and while mining bitcoin, they would still support increased block sizes... so they'd end up back where they began. As bitcoin miners supporting a protocol change.

BU's goal always to replace existing bitcoin, never to be a fork. Most coins upgrade regularly by hard forking. Steem does it, my favorite Nav Coin does it. It's non-controversial, but because there was a deadlock with bitcoin a simple upgrade becomes controversial because the core team were the ones unwilling to update the protocol to reduce transaction fees. SegWit was never a big enough upgrade to drastically reduce fees, hence why many opposed it... baby step vs. an actual step. That was the true debate but propaganda by certain core supporters changed the narrative on that issue successfully masking the facts.