My thoughts about this update so far (I do many informational searches on Google every day).
It feels like a lot of pretty, but not very genuine sites have been rewarded. Visually, they are appealing, content is well presented (not very original), but I don't feel connected to them; most of them are not genuine. For example, I studied a site that appeared on top results out of nowhere. Nice Wordpress template, many pictures. But it's clear, the site was designed for specific keywords in mind (suggested by main categories and keywords used). All blog posts were added in 2018, within a month (no consistency, suggesting the articles were purchased and published in bulk). Then I check a Disclosure -- I got it, the site "may recommend" or "endorse" specific products or services (the plus is it was disclosed in public).
I once visited a popular tourist destination. In main town, there were dozens of restaurants. A few ones in the best locations couldn't be overlooked as they seemed very shiny, pretty, in new buildings, parking space, splendid lights at night. I visited a couple of them; inside they were very nice too, air-conditioners, fashionable design, lights, and dressed-up waitresses. Food was pretty good. The problem - nobody or few people inside. Not because of the prices (they were, surprisingly, not too expensive). But there was no connection and authenticity. People (including me) would prefer to visit a "shabby" and old building, but one that you could feel they love doing what they are doing, and they do it well.
Same with websites - visitors don't mind a spelling mistake or some other irrelevant issues as long as there is substance and connection to the site. To me, this March 2019 update, in too many instances, kills the connection and promotes a shiny, but inauthentic package. On one hand, I'm not surprised that a Google "rater" who visits these newly-rewarded sites would feel they are of top quality, but when you dig deeper, the truth starts to reveal.
Regarding author bios - they have been heavily gamed. Shady "SEOs" create fake social media profiles and "guest articles," then they use the same fake name and credentials on their own bios (interconnecting / citing each other). AI thinks that the author is "legitimate" because the same (fake) name / credential is consistently listed and "confirmed" on LinkedIn, Twitter, Facebook, guest guest articles, and on his "About Me" page.