Nobody is eliminating dissent. Threads on divisive topics are filled with disagreement. It's flamewar comments that are the problem, because flamewars are so stupid, so predictable, and so nasty. They're the worst thing that group dynamics lead to on internet forums. On HN, we want thoughtful, curious conversation. If you don't want to post in that spirit, please don't post. If you're interested in using the site as intended, please read https://news.ycombinator.com/newsguidelines.html and take the intended spirit to heart.

I have no idea what "tech bro ideology" is but whatever politics you favor, I can give you a long list of comments bitterly complaining that HN is dominated by it and the mods are secretly conspiring to suppress everybody else. Edit: actually here you go—see the list here: https://news.ycombinator.com/item?id=23807579

All such comments are the same—the righties say it and the lefties say it, everyone says it. It is pure cognitive bias.