https://news.ycombinator.com/item?id=32759008 (Sept 2022)
https://news.ycombinator.com/item?id=21932634 (Jan 2020)
https://news.ycombinator.com/item?id=20456414 (July 2019)
https://news.ycombinator.com/item?id=18991797 (Jan 2019)
https://news.ycombinator.com/item?id=18984737 (Jan 2019)
I've posted thousands of explanations like that. The reason is not just to persuade/explain to individual commenters, but also to give everybody else a sense of where the lines are.
My sense is that if someone really wants to grok the intended spirit and make a good faith attempt to follow HN's guidelines, it's not that hard to do. Sometimes, though, people take the more obstreperous approach of "I don't agree with your rules and I don't see why I should follow them" (<-- I'm not quoting anyone specifically and I'm not imputing this attitude to you). In those cases, arguing about where the lines are doesn't help, and ultimately we don't have much choice but to ban such accounts. Often they then say "you're just banning me because you don't like my views", but that rarely has anything to do with it.
Some of this is cultural, meaning some people have a greater distance to "travel" behaviorally in order to fit the culture here. That may not be fair but there's not much we can do about it; there is a culture here that we're trying to foster, and that's only possible if commenters abide by it.