Can someone with a technical background explain what actually happened with the BIP-110 fork?

I’ve been trying to follow the whole BIP-110 situation, but I’m struggling to separate the technical issues from the politics and personalities involved.

But now that the fork has happened and appears to have failed to gain meaningful hashpower, I’m seeing BIP-110 supporters saying that the current BTC chain is “corrupt” or no longer the real Bitcoin, while some people are essentially treating the BIP-110 chain as Bitcoin. At the same time, there are plenty of people who are very happy with how things turned out and strongly oppose Luke Dashjr and the whole BIP-110 approach.

What I’m particularly interested in is the technical side, rather than the personalities. Why did it fail to gain enough miner support? How should we think about the argument that the existing BTC chain has become centralised?