They're hard to capitalize. You need a skilled founder willing to forego profits, or a group of well intentioned devs with management experience, to organize the business side of things. You have to figure out non investment sources of income (charge for services, donations, etc. maybe no ads or at least no ad networks if you're worried about privacy or ethics). It's a lot of work, especially trying to scale that up to where you can actually pay employees salaries and benefits.

It's one thing to have an open source model for software that doesn't necessarily need that level of official organization, but once you start getting into backend infra costs, you can't run that on volunteer labor alone, you eventually have to fundraise for infra costs. If only there were a public or community driven internet... it's too bad the peer to peer models (federation, torrents, etc.) don't work well for real time global communications. Centralized messages are much easier to read and write to.

That doesn't mean such a model can't work or isn't good, it's just much harder, and all for no profit motive.

Realistically I could see a bunch of ex FANGers pooling income into a worker owned coop and starting a tech collective, then maybe handing it over to a 501c3 at some point or just keep it going as a private company without outside shareholders. But someone had to organize all that, and it's not the traditional strong suit of devs.

Fingers crossed though. Would love to see something like that happen.