HN's rules exist for deep reasons based on many years of working with community dynamics. If you break them, you contribute nothing to resolving any social issue—all it does is rile up the other side and fan flames—but you do contribute to destroying this community. That's bad for all of us.
If you're feeling like venting about how wrong or bad someone is, don't post right away; pause until the needle goes out of the red. Then review your post and edit out any bits that still break the guidelines. That's what I do, and it's the only way I know to make this place work ok.
Hacker News is large enough that it lives in a precarious state: the forces that tear an online community apart grow with size and win by default. If HN's health points go to zero, it dies as a place for thoughtful discussion, so please take care with the health points.