Another idea is to prohibit mega-websites that comprise thousands of pages with content generated for free by distinct users from (a) using metadata generated from access to those pages or (b) serving advertising on those pages. Generally, prohibit rent-seeking by websites that delegate ongoing content generation to users on a large scale.

"Large group" could be as small as 200 or 300, or perhaps as low as 151.

A website operator who wants to publish pages managed and edited by 150 of his "friends" would be acceptable.

A website operator who wants to hand out pages to 100,000 people would not be acceptable.

https://journals.plos.org/plosone/article?id=10.1371/journal...

https://arxiv.org/abs/1105.5170

https://arxiv.org/abs/1011.1547

https://pdodds.w3.uvm.edu/teaching/courses/2014-01UVM-303/ou...

https://www.newyorker.com/science/maria-konnikova/social-med...

None of the links concludes that interactions with groups above the size of the dunbar number are detremental. None of this says that large gatherings are "unnatural" and certainly does not provide arguments why we should not allow gatherings or interactions beyond a certain point of people involved. It states that there is a certain number we can actively and comfortably manage, but nothing about the quite wide reaching things you postulated.