Because back then you had to know how a computer worked before you could get on the internet. And back then everything required a seperate irq# and if something had the same irq it would brick the computer and when modems came seperate. The only way back then you would get on the internet is if you were a college student,military,worked for the government or knew someone in those fields. And back then you couldn't get on the internet using a cell phone.

And seems back then there was more of a iintelligence with some users back then.