I would support a law requiring official government messages to be promulgated only via channels that do not require an account to view. It's not the most important thing to spend political capital on, but it would have the positive effect of directly interfering with government officials publishing their messages on proprietary login-only social media because it's the most expedient thing to do or it's the only thing they know how to do.
Isn't that just "the World Wide Web"?
The reason these sites require login is because they also want to control the resulting conversations, whether for moderation (generous) or selling your data (more likely).
Announcements/political campaigning doesn't require feedback in the same way so no reason for them to use X, FB or anything else.
Seeing the state of most conversations on X or FB, I'm quite happy with limiting the general public's ability to broadcast to the world.