Nobody called it 'eternal september' at the time. We called it 'The September That Never Ended.'
September was always a period sort of ... fraught, shall we say, with gross failures in established traditions and customs of how things were done, which we referred to as Netiquette. This is because September always brought a new class of students to the major universities where there was Internet access - people who wanted to be good citizens but simply did not know the customs and traditions and how certain things were seen and taken, and who had to be taught. And usually within another month or so the worst of the bad behavior would be over and we could move on.
And then there was The September That Never Ended, when AOL started providing Internet access to people who had no idea about Netiquette, and furthermore no stake in netiquette, and whose access would not be suspended for failures of netiquette, and who would not be losing anything much that they cared about even if their access to some particular forum or service were lost for such a failure. They did not give a crap about those traditions and did not want to be bothered to learn them. Far from being students who wanted to make a good impression on their classmates and professors and colleagues and who were very cautious of giving offense because they valued and needed the resources online, they were casual users on the net for grins and giggles. They didn't care about making a good impression on anyone. And their numbers were without measure. They just kept coming, first thousands a month and then millions. There was no way to have even trained them how to be polite if they'd given a crap and wanted to learn.
And that's the September That Never Ended. That's also my junior year of college, so yes, I'm an old phart.
[EDIT]: If I recall correctly, spam was invented either later that same year, or early the next. The first unsolicited commercial email ever was quite the shocker emotionally. People all over the country got into towering rages about it. There were so many responses from outraged users and system administrators demanding that this ass be kicked offline immediately that it took down every SMTP server within three hundred miles of the guy - It burned down not just his uplink, but also their uplink and everybody else who *connected* to his uplink. The consequences just in traffic from the outraged were so enormously expensive that they'd have lost money, hard, if they hadn't done it.
But he just went somewhere else and did it again. And then learned to spoof addresses so his next mail server wouldn't get burned down by the responses. And then people started copying him....