This is not restricted to HN. Other communities on the internet have this going on, only far worse (reddit is one primary example I'm thinking of).

Perhaps this ties into the engineering mind, which can be very quick to spot potential issues. That's one primary way you make your living as an engineer, by spotting potential issues in a process or activity before they occur and mitigating them. But this can quickly turn into simple bashing of someone's work if we're not careful.