I've seen lots of those studies, also. The problem is the selection of fonts vs just going for serif or sans-serif. Ideally, I'd want to give the reader control of the typeface - I love I can do this on a Kindle.
Plus, many of today's screens don't feel like "screens." Mac's Retina display has more of a paper feel than a computer monitor feel. Spacing also plays a big role. And light on dark? I use dark mode for social and related apps, but not for Medium. Go figure.
Different font styles don't just affect readability. The sans-serif font on one news site might be easy to read, while a similar font on another site might give the user a headache. They also affect "feelings" and comprehension. Last thing I want is for readers to absorb my work as if they're reading IRS instructions. :)