@fred9989 I completely agree with your assessment. You offer some great insights.
I've been saying for awhile I thought this was definitely an off-page problem and also noticed the keyword density signals.
I do think there will be either a roll-back or a massive overhaul of this update because the SERPs that I am monitoring (and even my own personal searches) are still returning irrelevant results that are outdated, spammy and low quality.
I actually started using Bing for my many of my own personal searches after getting frustrated with the Google results I was getting.