I agree with most of your conclusions here.
To me the problems are all automatically fixed if the platform moves to being solar powered.
The usual method and requirement of the platform owner obtaining their own energy by profiting from all users, is removed, if the platform becomes solar powered.
Its a long story, but this effectively would end up supplying unlimited energy and revenue to all users, by the platform inworld money automatically becoming a kind of kardashev money, that is money which effectively transports energy from the sun to all people, enriching them as well as any platform owners without limit.
The incentive to carry on owning the platform then is removed, enabling the owner to stand back to become just another user, and allow the platform to go open sourced, without losing any income.
Whether or not Zuck would stand back if that was to happen would be the test of whether he does it for love or money / power / privilege, because effectively he would be gaining nothing financially by retaining control as sole owner.
The quandary he faces by Kardashev Money is the same one faced by banks; wheher or not to give ultimate power to the people, the same power as owners / monarchs have always wielded themselves.
This seems to be why solar energy is so much maligned by monarchic political powers, it removes their fundamental requirement and thus their technical excuse to continue wielding political power over all others.
We no longer need them, when all is solar powered, all they need to do is turn on the Kardashev Money and walk away, allowing markets to regulate everything from that point onwards.
Markets become a single non-profit voting forum where everything automatically becomes something to be voted on, by anyone wishing to vote.
We saw a little of this when stimulus of 4tn per month was being issued in US.
I don't see why it couldn't be started again firstly in a platform, and maintained indefinitely, rapidly scaling to cover all things.
The first platform to do it would become the one for all things, including even energy companies, as none could do anything but merge with the primary mover after it went solar powered.
It could even be Medium that turns out to be the primary mover.