"Incredibly costly" + "I don't see how they would benefit" is only an effective argument against individuals and businesses whose continued existence depends on not wasting money. The state runs on taxes and executive orders.
You may not realize that one of the non-publicized goals of recent executive administrations has been to keep the official unemployment rate of war veterans low enough that it stays out of the public consciousness. This has been accomplished in large part by steering them into make-work jobs with strict citizenship or clearance requirements along with hiring preference points for military service.
The government probably does not care to intervene in our nerd talk, but it can afford to, and if that provides a minor political benefit beyond sticking loyalists in dubious, relatively-high-paying desk jobs, then so be it. If I were to attempt to promote state interests with respect to encryption and network security, HN is certainly one of the sites I would pay my subordinates to read and influence.
Don't assume that just because you think it is stupid and pointless, no one is actually doing it. That doesn't mean that anyone is, but you can't realistically argue that everyone is not.