I've used parts of the Internet where it was possible to give someone the cut direct. On Usenet (which consisted of "newsgroups" devoted to all sorts of topics, things like the Red Sox or specific programming languages, and threaded discussions of specific topics like last night's game or a particular programming question), people read and posted with software that included "killfiles." I could killfile a specific poster (if I found them tedious or offensive) or subject (if I cared about the Red Sox but not about the food served in Fenway Park).
That was silent, and could be turned off as quickly as on (if I decided that yes, I did care about hot dogs). However, it was entirely possible to make a post that said "$So-and-so, that was offensive. I'm kill-filing you," which became known as "plonking." and then put their posts in your killfile. Replying to something either by saying you weren't talking to someone (and why) or just with "plonk" was telling them and everyone else "I will have nothing further to do with him." It was considered very bad form to publicly killfile someone and then address them further; if Joe Schmoe is dead to me, I shouldn't get up and say "hey, world, I'm not talking to Joe, but my friend quoted this thing he said, and here's why he's wrong."
Like an in-person cut direct, plonking someone didn't mean the person who announced they had killfiled someone expected their friends to follow suit. I might look past someone at an event, even (in 19th century form) say "sir, I do not know you" before turning away, but that doesn't mean our mutual friends will stop talking to them. It does mean I'm telling everyone that I am that upset--which has the risk that some people will think that Joe Schmoe did nothing wrong, or that I'm overreacting, and act accordingly.
I've seen software that tries to reproduce killfiles on certain forum software, but it doesn't seem to have caught on.