The difference is that paywalled news sites require a login to access content that they themselves produced and published, while Twitter/X now requires a login to access content written by other people.
In other words, paywalled news is a first party content provider, but Twitter is just a third party who inject their mandatory login between me (the reader) and the writer so they can make some profit by showing ads on the content.
That's fine, but authors should consider if they want to publish on a site like that when there are so many other options.