What? No it wasn't! You used to be able to view entire Twitter threads without being logged in. It was also possible to go to someone's account page and see their posts in reverse chronological order. The latter went away shortly after Musk took over. The former took a little longer, but is now gone as well. In many cases you can't even view a single tweet without the site trying to get you to log in.
There was briefly a log-in nag popup that would appear on scroll.
That disappeared and Musk got lots of praise for it, probably entirely unwarrented but it was basically the only thing that improved post-Musk. Then it came back with a vengeance.