Same shit really. I remember it being called endless summer because in the early '00's-'10's when summer would start kids would flood message boards and the quality would tank. When the quality stopped going back up once summer was over people called it the endless summer!

In the old days of bbs and the like, September was the bad month because of exactly what you said. Internet access wasn't ubiquitous so when college started you got a bunch of newbs spouting dumb stuff.

Basically 10-20 years later it stopped being September that was the worst and it became the summer. Now we are experiencing endless summer/eternal September perpetually because nobody ever leaves the internet.