In the late 80s/early 90s Tress MacNeille - major voice actress - got stalked by an obsessed loser fan to the point where she stopped going to conventions for a while. He looked exactly like the OP pic.
A guy that looked awfully like OP's pic would creep on the VERY small number of girls at the first few BotCons (which had a few celebrity guests).
And artists at cons have always had to deal with creeps wanting to commission porn, even if that's something the artist really doesn't do.
Aaaaand it's really not an exaggeration to say that at con panels you will regularly get That Guy, who wants to just point out "flaws" in what the show put out. Conventions (especially big ones) have gotten better at screening questions beforehand, but you still get the odd moment where everyone in the room just sits there going "oh my god shut him up" as someone goes full autist.
There's always been people in fandoms that make people working in the industry want to just (1) take a bath, and (2) animate something telling people to PLEASE GET A LIFE. https://www.youtube.com/watch?v=lNJ6dFwh8a4