It is not difficult to block traffic you don't understand. Require end users to only use plaintext protocols, even go so far as install your own certs to MITM them. Make it a requirement for using the service.

Just charge any business that needs encryption several million per year, and everyone else can get fucked.

Even beyond the FCC backing this sort of business now, what other part of the government would care to stop that? The only other parts in charge of anything touching on communication technologies are all law enforcement and they are already explicitly stated that they want access to all encrypted communications