Using mono ulture as a word doesn’t change the meaning here. If anything, its a pathway for the foal you ascribe.

Of course it does. Federation can be a monoculture too (as it is with plants). A bunch of centralized (technically federated in IRC’s case, but united) services, like with IRC, can be not a monoculture.

Monoculture is important because one virus (of conspiratorial nature, like backdoors and architectures with planned life cycle, like what I suspect of the Internet, or of natural one, like Skype’s downfall due to its P2P model not functioning in the world of mobile devices, or of political and organizational one, like with XMPP’s standards chaos and sabotage by Google) can kill it. In the real world different organisms have sexual procreation, as one variant, recombining their genome parts into new combinations. That existed with e-mail when it worked over a few different networks and situations and protocols, and with Fidonet and Usenet, with gateways between these. That wasn’t a monoculture.

Old Skype unfortunately was a monoculture. Its clients for Linux (QT) and Windows and mobile things were different implementations technically, but with the same creators and one network and set of protocols in practice.

I still think the existence of crypto is a massive boon to many

That’s the problem, it’s not. You should factor psychology in. People write things over encrypted channels that they wouldn’t over plaintext channels. That means it’s not just comparison of encrypted versus plain, other things equal.

even in a “flawed” implementation with the “control” being on the side of corporations - tho if they are smart, they’d never store the keys themselves, not even hashes.

And that’s another problem, no. Crooks only steal your money, and they have adjusted for encryption anyway. They are also warning you of the danger, for that financial incentive. Like wolves killing sick animals. The state and the corporation - they don’t steal your money, they are fine with just collecting everything there is and predicting your every step, and there will be only one moment with no warning then you will regret. That moment will be one and the same for many people.

Unless you’re part of the signal project, I doubt you know the exact implementation and storage of data they do.

What matters is that the core of their system is a complex thing that is magic for most people. You don’t need to look any further.