Even ignoring the political misinformation that is rampant on these platforms and often promoted widely by the platform because it is inflammatory and gets lots of engagement, they also severely punish posts that link away from the site, which public safety and government accounts obviously need to do. It's a hazard for public safety info to be targeted primarily at a feed designed to bury it. Even if you're following those accounts on Xitter or facebook, they're effectively never going to show you their posts.