Not sure about the details with Freifunk, but Guifi has collaborating companies who basically operate like ISPs but connect you to Guifi + you get a internet connection via the Guifi peering the installer helps you with.
The idea that anyone is too firmly entrenched is always true. Until it is not. We are not still using horses, nor casting bronze tools. Nor do most ships sail. We (mostly) don't burn coal anymore. It would have been utterly insane to imagine replacing any of those entrenched technologies. That is the "follower" syndrome.
The context for a new kind of internet is very different now, than when the internet started. That changed context provides an opening for new ways to do things.
A crucial and hard piece is that it has to be paid for. As much as you need a parallel networking stack you need a parallel business model. Yes, the current one is too firmly entrenched, etc.
Of course the problem is that what can be forked already has been. Federated social media. Distributed git hosting. However most "essential" uses are centralized and often also commercial in nature. If you fork Amazon you're ... still Amazon. That sort of thing.
This is basically "just don't use things you don't enjoy" and the trouble of our time seems to be the number of people who can't or won't do that.
It's somewhat an age thing but also definitely a lot of people in all generations never learn it: you can just stop using things. Walk away and suddenly find you never want to look back, and if you do it's entirely unappealing.
