Even in the days anything more insidious would happen over direct mailing, or direct spam through the mailbox. Even knowing what magazines someone subscribes to is not obvious if you don’t catch the mail staff or check the garbage, which would be roughly equivalent to stalking someone online and checking their accounts followings and network.
I think as long as people are trying to build communities, there will be channels to get what other people are thinking/reading/discussing. It will be more tricky with true direct one direction messaging sending “orders” to an army of followers of an ideology.
CNN et al which all have questionable at best propaganda/war drum records are still pointed to with appeals to authority.l, etc.