It's not really about credibility, it's about status. Bad behavior -- and being this rude is bad behavior -- is much more tolerated in high status individuals, in every type of community. Just like (extreme example) how senators and Goldman Sachs CEOs can walk away with a slap on the wrist and a little bad press, where you or I would go straight to jail.
If it were just about the value of the information conveyed, people would do their own research when a person is "brutally honest" with them, and decide whether or not that information itself is credible.
The confusion lies in the fact that in a community like HN, that worships logic (and also success), those things that make you "credible" are what make you a high-status individual. That means even the statements those high status people make which are NOT credible themselves will be accepted, or only gently rebuffed. (Which is a big reason why you don't see much criticism of pg here, or when you do, it's very respectful, vs other authors, even when he writes something ridiculous.)
If it were just about the value of the information conveyed, people would do their own research when a person is "brutally honest" with them, and decide whether or not that information itself is credible.
The confusion lies in the fact that in a community like HN, that worships logic (and also success), those things that make you "credible" are what make you a high-status individual. That means even the statements those high status people make which are NOT credible themselves will be accepted, or only gently rebuffed. (Which is a big reason why you don't see much criticism of pg here, or when you do, it's very respectful, vs other authors, even when he writes something ridiculous.)