I would argue that it's those people (citizens/companies/orgs) who did the important choosing here, not Meta. It's more cheap and accessible than ever to make a website that isn't dependent on social media, and there are tons of alternatives for connecting groups.

The elephant in the room, I think, is that most people actually feel that Whatsapp, Facebook Groups, etc. have no important downsides. I can't prove it, but I suspect that more than half the people who are involved in such network-effect communication (let's say, all the categories you described, the non-1:1 communication that takes place hosted on Meta platforms) find it to be very convenient, not least because they're already on those platforms by choice for recreation.

THAT is why it's so hard for the minority who philosophically hate ideas like targeted ads are unable to convince the masses to all move to Mastodon, or to one of the hundreds of lesser-known platforms that don't have all the same baggage (in their eyes). It isn't for lack of options. It's because at least a plurality of people are fine with it.

So the argument to effectively nationalize Meta, simply as punishment for getting normies to like their apps so much, because a minority of people just think it's wrong to be good at targeting ads, seems extreme to me.