> Has it, though? I don't think we are any step closer now to dropping email than we were 25 years ago.
I think OP meant that there's been a significant decrease in usage. In my case I can definitely relate to this for personal communications, I no longer send emails to personal acquaintances, I mostly use email for professional purposes, so I think OP's point stands.
> Could be the lack of marketing (because there isn't a corporation or venture capital money behind benefiting from exponential user base growth) and critical mass/peer-pressure as a result
Maybe marketing would work, but a killer feature is way more efficient, especially in the long run. WA offered users a way to text using the same phone numbers for free in countries where you had to pay. Decentralization, like being-open source, does not provide short-term benefits to a user, so you still need distinguishing features.
> did you know that WhatsApp runs on XMPP [...] All those silos could open federation and let messages be exchanged across services but chose not to do so (including Signal), because they have more to gain in keeping you hostage.
WA also uses the Signal Protocol, which I assume is not directly compatible with OMEMO (or this name wouldn't exist). From the little information I found, it uses a customized version of XMPP, which is also probably not directly compatible with XMPP.
My point is that it's not as simple as setting COMPATIBLE=TRUE to make every network compatible with each other. I doubt Facebook deviated from the base protocol just for the sake of it (and there are simpler ways to prevent 3rd party clients), they wanted to implement something which was missing. They wanted to customize XMPP to add features (pretty much Moxie's argument against federation).