Earlier quoted context omitted.
It is somehow sad that "caring about content quality" is considered SEO and not just making a good website. I think more than half the things you mentioned are only good SEO because search engines want to send people to websites they will like reading. I think when that is the case, we should be crediting people for making good websites, not good SEO.
SEO changed dramatically over the last 20 years. Thankfully, we are today exactly at a point that you described (it all started with Panda in 2011). As you'll see below, getting there was not just a technological challenge, but also one of fixing misaligned incentives. Prior to 2011, Google enjoyed a mutually beneficial relationship with content farms which splattered their pages with AdSense ads (and Google ranked t…
“Google Panda is a major change to Google's search results ranking algorithm that was first released in February 2011. The change aimed to lower the rank of "low-quality sites" or "thin sites", in particular "content farms", and return higher-quality sites near the top of the search results.”