There have been some very interesting experiments in this area. Going back to the 90s, smaller website once gathered together to form communities under a single subscription fee. In some advanced groups each website was given a share based on traffic. This allowed a single reasonable subscription to back a great many independent websites.
As with most things on the internet, the porn industry did it first.
That subscription might be reasonable for a middle class person in the US, but way too expensive for the average person in a poorer country. Ads put everyone on the same footing.
And if you want to do research on a topic across many different websites, it'll happen that they won't all be in the same community, so you'll have to pay subscription fees to many different communities, sometimes just for a single page view.
As with most things on the internet, the porn industry did it first.