Everyone who likes alignment claims to understand it, but I guarantee you that your individual understandings don't match up.
And stop accusing people who dislike alignment of not understanding it. I get what it's supposed to do and it is garbage at it. It tries to make objective descriptors out of subjective concepts, making it useless for actually communicating all but the barest of basics of those concepts.
Moreover, what people who 'understand' alignment don't. It was supposed to be a team jersey. You were on the side of Chaos or Evil and you fought against the agenda of the other guys; it had nothing to do with your actions or personality. Over time it's mutated into this weird war of prescriptive vs descriptive tag for action or personality but also the physical underpinning of the cosmology.
Also, there's always this idyllic vision of a DM-rich environment that's not as painfully toxic as con pick-up games or that everyone has the desire to DM. I do DM a lot, but sometimes you want to play and it's still just as annoying to pretend alignment matters when playing under someone who uses it.