If the telephone system had the same moderation as HN then I would suspect that indeed it would seen as oppressive if they were listening on all telephone calls and banned users who they deemed inappropriate citizens.

We only have one telephone system so being banned has a rather large impact as it is an essential service. So maybe we should ask what platforms are like other essential services. Radio is an essential service. What about Youtube? The telephone system is an essential service. What about Skype? I think libraries are also seen as an essential service, so what about Wikipedia? And then we have HN. How essential is HN?