Blocking users who are not logged in has farther reaching consequences that aren't readily apparent. For example, there was an AMBER Alert a few days ago with a short link to see more info. The link goes back to a Twitter account/tweet. All that time sensitive, useful information was behind a wall where you can't see it unless you log in. Most people aren't going to create an account just to do that.
Blocking users who are not logged in has farther reaching consequences that aren't readily apparent. For example, there was an AMBER Alert a few days ago with a short link to see more info. The link goes back to a Twitter account/tweet. All that time sensitive, useful information was behind a wall where you can't see it unless you log in. Most people aren't going to create an account just to do that.