It's funny to see this all go full circle. messenger.com was spun out of facebook.com to try to build a new platform. They promised interoperability with Instagram and WhatsApp accounts, although they never did a good enough job that you could just use one account across them.

Facebook really could have been the default online identity provider if they weren't such an abhorrently shitty company. In the early days, you wouldn't even ask for someone's number - you'd just chat on Facebook.