Based on my observation, it seems that Big G has cleverly categorized links into the spam category - for those spam links, and when grouped in such a way, these links have no value whatsoever, thus making them useless for practically anything.
I noticed that those spam links used to work great 5 years ago, and they gradually decrease in link power/juice, and up until recently, building these links contribute no value at all for link building efforts - it does not move your SERP up or down at all, meaning they are practically useless.
So with the link juice devalued and making the spam links virtually useless, you can't use those to increase your SERP, and it also does nothing much to negative SEO as well.
I also noticed a drastic drop in link removal requests - perhaps that also has something to do with the devaluation of these spam links, in that aspect.