All it takes is one browser 0-day that gets distributed on an ad network. A large segment of the HN crowd is still executing untrusted JS on their computers and opposed to blocking their source of income.
At least back in the day when Flash was still a thing, it was a common issue for "enterprising" people to buy advertising slots, even on reputable media, and spread all kinds of malware via them.
Also, 0-days are generally hard to come by in browsers these days, the libwebp one was initially developed by NSO for example; and tech support scams are not that profitable.
It's too simple. People don't know who's trustworthy. And I don't make house calls hundreds of miles away.
Business opportunity for a "Local Trustworthy Techs"? Heck, the Goon Guys will search your drive for illicit material, and if they don't find any, they'll install some (If I recall some horror stories correctly).
Hopefully they uninstalled the software once the printer was working.