That's how every opinion anyone's ever had works. Everyone has a mental model, which they use to understand the world. If you have a problem with the specifics, address them. Otherwise, you are simply appealing to authority.
That said, Internet discussions are run on Cunningham's Law - you say what you think you know, and others will call your errors out, or challenge your assumptions. As long as people don't read any single comment as gospel, but consider the whole discussion in context of their own knowledge, applying basic critical thinking, everyone gets to train their reasoning skills and learn something. I'd expect this to be a baseline on HN.
I'm confident being the protagonist of that XKCD is a rite of passage in this industry :).
In general, this can't be a way to move forward as a society if people just make stuff up.
Closely related XKCD: https://xkcd.com/1831/