This is some food for thought. It's been a truism in science during my career, at least my early career, that there are more and more papers in science. It looked to be the case in my field, where a glance at the library shelves showed later years with more shelf space than earlier years. The "publish or perish" issue also contributes to having more and more papers, each one constituting something closer to a minimal "publon" rather than more comprehensive studies.
The article suggests that increasing collaboration may reduce the total number of papers. I wonder if it has to do with drops in graduate enrollment in the 1990s myself, or with the tightness of permanent jobs and funding we hit around the same period. I'll have to read the article in greater detail. In any event, I think this is interesting and there should be a national discussion about it.