That said, the fact is that the mainstream alternatives are handicapped by their own success and are afraid to change anything of their core features. Starting a new platform would be an opportunity to revisit many of the original design choices, and perhaps one could do surprising new things at that point.
I think the co-operative model is interesting economically as well because as far as I can tell, there are at least some cases where it does work out to be economically stable on a reasonably long term basis (decades anyway), and I presume it changes things a lot, organizationally, if the main goal isn't just "lowest common denominator software for the sake of maximal mass adoption and growth."
Facebook and Instagram had no trouble stealing the concept of 'stories' from Snapchat and Facebook also copied their augmented face masks.
Did WhatsApp use a lot of open source stuff under the covers that we could leverage in building our own secure person to person/ group chat platform?
A disrupter would have to have even less friction but would be competing against a product that already has a significant network effect and a very generous backing by Facebook. I'm speculating that FB will eventually nudge WhatsApp users to Messenger, or find a way to gradually merge the services to the point where they are identical, especially w.r.t. advertisement.
In that respect, it was brilliant of FB to acquire WhatsApp: not just for the users, but to make it hard for any newcommer to disrupt things (hard to compete againsts free and frictionless).
There are many (open-source) solutions for building your own secure messaging system, XMPP and others.
I'm happily running (I should also disclose: developing) my own server and talking with friends and family who use e.g. Conversations as an alternative to WhatsApp.
The only friction to the end-user is the same email/password request every other service makes, but you want to use CL because it's the de facto place for listing your apartment or whatever.
The table stakes are another reason why this endeavour won't happen as a small effort.
What the big platforms have done is eliminate friction at all the critical parts, to make it easy for users to onboard, easy to share, easy to grow within the platform, and of course hard to leave.
I've been thinking about a low cost but not free platform too. If it ever happens, it will have to be AT LEAST as frictionless and enticing as the existing platforms. The table stakes are very high. Since cost in of itself is a source of friction, that means the rest of the platform needs to be even MORE frictionless.