The '90s was a bit too soon for that. Most people using the Internet then were still on dialup, to the extent they were connected at all. There weren't that many DDoSes yet. Even the Trin00 DDoS in 1999 only involved 114 machines.

DDoS for sale were not a big thing until Bitcoin. You couldn't transfer meaningful amounts anonymously.

And no, lol. There were no million machine botnets in 90-s. You could DDoS the entire countries with a few dozen computers, Slammer did that accidentally with Korea.