What I found was... exactly that. There were definitely ads there, but they took up 20% or less of the space, roughly the recommended split for social media anyway. Every time I scrolled, I found an interesting story. When reading the article for the first time, I wrote "Facebook's like doesn't mean
"like": it should be relabeled "see weird stuff kind of but not really
related to"... but I guess they can't fit that on one line."
In continuing my study, it seemed to do that, more or less. I observed that certain friends who posted more (and since I liked everything, therefore had more likes) would show up almost every time, whereas friends who only posted occasionally, only showed up occasionally. On the whole, however, this was an almost infinitesimal correlation. In fact, several times I switched between my news feed as shown, and "newest posts" and there was very little difference.
This leads me to conclude that Facebook has two Tipping Points of becoming a negative experience. The first is the obvious one: like too many ads, and they take over everything. The second one is more subtle: if you spend a significant amount of time on it, you may end up accidentally curating your content in the wrong direction. Both are equally bad, but there can be a solution: don't use Facebook that much. Works for me.