It destroys the previously implicit contract that the writer actually spent a decent amount of thought and time into the writing, and that the ideas expressed are theirs and original.
I don’t mind good usage of LLM assisted writing, but if the author can’t even be bothered identifying the most obvious AI tells, I use it as a proxy that the author probably but very little effort into the article.
It’s also often a horribly verbose style, where the same ideas could be presented with 20% of the prose.
It’s also ruining the entire experience on web communities (although here on HN the moderation team seems to get a hold of keeping them at bay at this point, much appreciated).
All in all, it’s objectively a net negative for the readers, and serves only the author.
I prefer original, less coherent articles that are genuine and where I know the ideas expressed are really the author’s and not the LLM’s inference.
Last but not least, I don’t think the grandparent you’re replying to was particularly hateful in the grand scheme of things.