It is possible to authenticate and remain anonymous. There are authentic data techniques I write about that allow for users to prove they have been KYC'd and are human but Twitter never learns anything about them. The approach also gives a verifiably encrypted "correlation identifier" to Twitter that Twitter cannot decrypt but can be walked back to the KYC vendor to identify the user if they break the law. In the United States, that should only be done under a court order such as a search warrant. This creates perfect 4th amendment privacy. That is the compromise the framers struck here in the United States.
To put it simply, there are applied cryptography tools (not Web3 or NFTs or blockchains) that allow for these kinds of digital interactions. I call them "cryptographic qualifications" because they only reveal a simple "yes I qualify to use Twitter" or "no I do not" but none of the underlying private data is revealed--or even transmitted--to Twitter or anybody else.
I hear your concern about authentication. I share them with you as well. But there is a compromise in the United States Constitution that we can enforce with cryptography so that we can all have nice things.