You're not entirely wrong, but that's been baked into HN since the beginning, and yes it is absolutely the owners' choice to make. It's their house, their priorities, their rules.

But if it helps, they didn't even used to warn people beforehand. PG just pushed the button on you and you might not even know you were shadowbanned for years. At least you can vouch up unfairly banned comments now, and the mods give you warning.