This should have been a blog post and not a forum post, but I was replying to an excellent post by Spirituality that set me off.
In a stupid reversal of what makes sense for a blog vs. a forum post, I will excerpt possibly the most useful part of my TL;DR post and quote it here:
Google’s end goal is to serve up the most relevant content; it’s treating “quality” not as an intrinsic value but as a component of relevance.
Start with Spirituality’s comment above, then grab a cup of coffee and read my natterings that followed. (or not.)