I, on the contrary, disagree with the single point of failure point. Nothing prevents Signal to internally build n systems that federates together and can be down/broken independently.
Foundations, like companies or any organization, are composed of people. People can and do get replaced, corrupted or bored and move on, they can eventually decide to take the organization in a direction unlike what was originally intended. Takes more time and effort than just throwing a pile of money at the founders and shutting it all down, of course.
