Because it was common back then (more like 80s and 90s)...You also had typewriters/word processors pounding away...Now they're not and they'll stand out and yes, they'll be annoying.
Personally, I'd be happy to see someone with a Mech board..would probably start a conversation about it...bring in some other stuff...maybe convince them to go another direction and if not, just let them know it is pretty annoying. Most people, if they didn't realize it before, will realize how annoying it will be then..and if they don't care, *shrug*, I don't care about a formal complaint then...The thing is, the person would have to be completely clueless and completely self important to not take anyone else (their co-workers) into consideration so it is likely to never get to that stage...