The spam isn't just for things that are savory. The spam can be for unsavory things, propagandizing, griefing, or advertising outright illegal things.
I don't want to have to wade through a shit ton of nazi bullshit or ads for whatever is the silk road replacement nowadays in order to take a beat after work to read shitposts. Dealing with inane stupidity shouldn't be the bar for what people have to put up with to interact with each other.
Because not as many people were on the internet, the technological and social landscape is completely different today compared to twenty years ago.
Moderation has also pretty much always been part of the internet in some degree, I don't believe that the internet being enshittified has nearly as much to do with the presence of moderation, good or bad, as it does with fundamental problems with the constant monetization inherent in capitalism and the adaption of social media influence and recruitment strategies by the far right.