I was trying to find some way to explain to people why google results used to be good (back in the days when signal to noise ratio was much better) and now are

I was trying to find some way to explain to people why google results used to be good (back in the days when signal to noise ratio was much better) and now are crap (combination of endless social media, marketing blogs, etc, and of course google's own need to generate money and hence pushing sites/advertisements to the top). I think you've captured it very succinctly. SEO'd to death, stealing this, thanks!