Signal is the world’s most widely used truly private messaging app, and our cryptographic technologies provide extra layers of privacy beyond the Signal app itself. Since launching in 2013, the Signal Protocol—our end-to-end encryption technology—has become the de facto standard for private commu...
Most of the cost from not moving from requiring phone to be connected to people’s accounts and not desiring for the central server to federate with others.
Yep in the last two or so years it should have become even more clear for people how important federation is.
According to the article, like most companies, it’s the people that are the most expensive part at $19M.