But I think it's the primary way the state finds out what we are doing, so it then can exercise it's violence, if it finds us doing something that it doesn't like.

The first thing police do nowadays is check social media accounts when there's a crime, whether it's a thought crime or not? So by reducing our reliance on online services, we can diminish the ability of the state to police our lives?

Or maybe I'm wrong here (tired, and need a rest, so I don't end up spamming HN)?

In the US, at least, the state definitely doesn't have a complete monopoly on violence. For better or worse.