I don't believe that's true, in that visibility only disappeared after Musk's takeover. It's hard to find old news with modern search engines, but here's one article from 2023, post-Elon, that matches my memory:
> If you currently try to access Twitter without logging in to your user account, you’ll be unable to see any of the content that was previously available to the wider public. Instead, you’ll meet a Twitter window that asks you to either sign in to the platform or create a new account, effectively blocking you from viewing tweets and user profiles or browsing through threads unless you’re a registered Twitter user.
https://www.theverge.com/2023/6/30/23779764/twitter-blocks-u...
It looks like it was pushed through by claiming the site was under attack, and then access was never restored. In any case, it was one of the things that pushed me off X.