The use of the term in this context is calling out the specific vulnerability of using the walled gardens of Facebook/Google/Apple and the other behemoths. By your literal correctness of the term, there is no possible way to operate on the internet, since you don't own the land and the network cables from your servers to the clients.

Pulling one's head away from their rear end provides the vision that relying on specific vendor platforms, with their own goals and interests sometimes counter to yours, is different from using a colocation for servers.