Well, those were "phreakers."
In the 70's, "hacker" was a person who "hacked" out the credits from public domain software and put their own name in it for resale. And you bought it anyway because software was so hard to come by.
And then those intros eventually gave rise to what they called the Demo Scene where "hackers" would gather to see who could write the coolest visual/audio experience under various levels of constraint.
And many of the graphic algorithms derived by hackers in the demo scene gave rise to the algorithms used in today's 3D videocards.
I recall seeing a website that collected a large number of such intros, I think posted here a while back. It was very aesthetically interesting and quite pleasantly nostalgic and now I can’t locate it, hopefully some other visitor to this thread can.
Is there anything to support this?
The real problem was access. There really were very few computer stores. I remember driving nearly an hour to get to one of the very few computer stores in northern New Jersey (Wayne Software).
The other option was to buy software from those tiny ads in the back of the computer magazines. Those were where you really got the "hacked" stuff. Sometimes you'd see an ad for the same program on multiple pages. And even though it was hacked, you still had to pay $99 for a very basic text editor.
Even blank floppy disks were hard to come by. I remember having to get floppy disks at the famous FAO Schwartz toy store in Manhattan because it was one of the few non-office supply houses that had them. I think they cost something like $5/piece ($15 in today's money).
The demos in keygens and intros were commonly known as "cracktros".