Because the people claiming so are actually bad at coding. I suspect a lot of them actually work in non-coding positions. And while I can for sure see how LLMs can be useful, they code at the level of a junior dev fresh out of college, if I am being generous.
Techbro astroturfing. You don't really see the same level of OMG AI on other forums like Reddit. Same thing happened with cryptocurrencies, HN was inundated with plugs for them and the same behavior was downvoted severely elsewhere.