@samueljohnson Glad you asked. Signal is a centralized service run on Big Tech infrastructure. You can decide to trust Signal as your service provider; That’s absolutely fine and reasonable even. But they don’t allow federation or inter-op with anyone who wants to make different choices.
#XMPP gives you that choice. Don’t trust me to be your server operator? That’s fine: pick a different one.
Donations to Signal are directly funding Amazon, Google and Microsoft.¹
¹: https://projects.propublica.org/nonprofits/organizations/824506840