Of all the things you listed, which are surely important, you also said the single most important factor in the end:

> once you have enough users, that becomes its own reason to join. There's not really a way to jump start it

So, a monopoly that was lucky enough to be the first one to solve some (minor, if I may) technical problems.

We need forced interoperability. Facebook has no right to control the communications of so many billions of people, just because Whatsapp got lucky and then facebook acquired them.

Who knows how much data they harvest.