Imho, info decay took off when social metastasized, which is to say ~2010+.
It was an interesting time, because (from memory) 2000 was still "It's pretty complicated for average person to create and post content on the web" and transitioned to 2010's "There are highly polished, easy to use, free SaaS solutions that a trained dog could use." With mobile versions of same in the next few years. (All dates mass market penetration, not first release)
There was a direct correlation between ease-of-publishing and less intellectual discourse on the web.
"Info decay" was definitely a good way to put it. It wasn't that people were necessarily dumb or angry, but that there was a lot more honestly incorrect information online.
Before, there were crackpots, but it was pretty easy to tell they were crazy.
Having seen both, the banal wrongness is far worse.
I think that's one reason wikipedia really took off ~2005+. People were craving an easier way to get even roughly-right information.