Shadowbanning certainly exists on all social platforms. Light version of it is how Facebook sells ad services - no one following your page sees content unless you pay.

You can add suppressing on hn to the list:

https://news.ycombinator.com/item?id=37785072

Per dang, that's a consequence of user flags: <https://news.ycombinator.com/item?id=38311933>

This is hardly unexpected for profound allegations without strong supporting evidence, and yes, I'm well aware that presentation of any evidence would be difficult to validate on HN, such that a third-party assessment (as in a court of law, for example) would typically be required.

I'm not claiming that HN has a stellar record of dealing with unpleasant news or inconvenient facts. But that any such bias originates from YC rather than reader responses and general algorithmic treatments (e.g., "flamewar detector") is itself strongly unsupported, and your characterisation above really is beyond the pale.