It is because HN is contrarian and behind the times.
I work at a big tech company and I don't know a single person that still hand writes code. Most people haven't hand written code for at least half a year now.
I do wonder what sort of bug is making its rounds on HN that people here find this so shocking and unbelievable.
The bug is called "applying actual engineering principles and critical thinking".
The absolute vast majority of people who point out AI's downsides have used it and use it. People who uncritically write things like "I work at a big tech company and I don't know a single person that still hand writes code." scare the shit out of us for a good reason.