Interesting article. If I'm not wrong, I believe the term was coined on one of the VHLM draft streams I hosted in the early-mid S70's. We had gotten pretty deep into the draft, to the point where most players didn't have a single forum post outside creation/waiver acceptance and we were sort of struggling to come up with something to call them. I think we were just calling them welfare users, but obviously there's a large scope of welfare users. Someone came up with "clickers" on the spot and it literally just clicked, since it pretty accurately represented that subgroup of users.
Out of curiosity, do you consider pressing keys to be clicking? If yes, then I think everyone is not a clicker . If no, maybe we should revisit what it means to "click" something lol.