It's hard to do any kind of objective comparison like this when it comes to SEO. It takes months to see any effect and even then you will have to speculate.
You could try to remove GA from half the pages on an existing site one day and see if those subsequently drop more, if you have enough pages to experiment with.
There is some evidence that older pages (>10 years old) drop out if they don't use any of Google's plugins. I think it was Tim Bray who was one of the first who noticed [1]
I also found another case of a lot of un-googleable reddit pages from only 5 years ago. They just don't exist on Google anymore even though they are linked from e.g. peoples profiles who commented there. Someone decided that Reddit is not important, or maybe there's some broader exclusion criteria in place.
I didn't read the comments, but the article didn't mention anything about Google plugins, did it?
I suppose it's possible Google used GA stats and maybe even content fingerprinting to determine if certain pages should be indexed, or reminded from the index, and how often to crawl them if indexed.
True, I think it was in various discussions here on HN including maybe under Tim Bray's article too. Same kind of rumors were circulating regarding AMP. There is still no direct evidence that Google's web plugins matter, but at least it seems like spammy websites that are fully equipped with Google's stuff get favorable ranking. And vice versa, you won't see high ranking spammy results that are not crammed with GA, Google Fonts and what not.
You could try to remove GA from half the pages on an existing site one day and see if those subsequently drop more, if you have enough pages to experiment with.