Twitter is those public-use bulletin boards at the entrances of grocery stores.
(are those still a thing? Practically every store of any size had one in the 90s, at least, but I haven't paid attention and can't for-sure recall seeing one in years)
This is like a big private club that allows anyone to enter and has effectively taken the place of a town square, due to (among other things) lack of such a public project. It ought to be owned by the government, but we've privatized it.
