I think the reason is simple. Previously, the internet didn't have a real purpose, so everyone on it was mostly for the weird/fun stuff. Nowadays, as mentioned in the blog, it also has legitimate serious uses, so by definition the ratio of weird to serious is lower.

But I think expecting the internet to only be one way is not only naive but also unrealistic. You may enjoy it being that way, but not everyone does, and the internet is for everyone. There's something for anyone, you just need to find your corner of the web.