I think it's a combination of less presence/engagement in niche content, sorting methods not quite being there, and not enough discovery without going out of band to find things
One thing I really miss is the science groups, askscience always had great debate that I haven't yet found here
This actually gets me thinking... Is anyone actually working on an aids vaccine? Maybe mRNA could do something there, theoretically it should be able to grant pretty much any type of immunity you can have naturally