It turns out the budget shows the phone number registration problem: the costs to deal with phone number verification seem to be $6MM, which seems to be 10% of the entire budget.
If Signal staff are reading this, I'd gladly pay $100/year for a phone-free solution for all users.
How would it be worse?
You might understand that it's a bad idea, but that makes you an outlier.
Let one communicate from a computer (or phone) with a username+password account, with people who use the service with phone number account.
This without the mechanism Whatsapp uses, where you can use it in a web browser, but it's still linked to your phone.
This is why it still has a stronghold as well…
Given the choice between SMS and a service that provides the same functionality is free, superior in most ways, borderless, etc. the choice to use whatsapp is obvious.
You could even automate the bans by banning anyone who gets blocked by more than two people they sent messages to, which anybody can avoid by not sending messages to people who would block them, and if it happens to someone innocent, it's still only another $10 to reactivate your account.
Can't say I've ever gotten any psycho responses from it though.
Also preferably clearing differentiating username and phone number messages.