Comment by jeroenhd
... which requires an addon to the browser, or for it to be built in specifically for that company.
That's not something companies like Matrix can use. If you're installing software already, why not skip the browser engine and install a full Matrix client instead?
I wasn't responding directly to Matrix's use of MAS. More generally I aimed to make the parent poster aware of a new technology that allows for private authentication, which they claimed was impossible.
Privacy Pass is currently being standardized by the IETF, so we may see more widespread adoption eventually: https://privacypass.github.io/