Broadly speaking, that might be true. But according to supposed experts who have spoken on the topic, Google rankings are not always based purely on algorithm-based heuristics. There is non-trivial manual intervention. SEO firms will always be - if you sold raincoats in the Sahara, I'm sure you'd always find a few takers. The edge over the competition they might offer may very well diminish.
I am particularly interested in this statement: "Then I realized that it wasn’t because of kw density that I was getting better results, but because the content had been updated." Despite the best SEO efforts, does the updating of content matters? I have a PR5 blog which has reached a certain status and not been updated regularly as I am more focussed on my current blog. Will PR be affected?
Google has been doing more hand reviewing then ever before. You can even see sitelinks that have been hand reviewed.
Google and other search engines will always be a set of rules/ algorithm to fathom out. Optimisation will always be possible and desired as there will always be people who want to get to position 1. Content itself can be optimised.
Google would be SO wrong to use bounce rates at all in the algorithm... it way unfairly punishes the website that gives the information to the user quickly and to the point right on the first page
Perhaps I'm understanding the concept of an algorithm a bit too mathmatically but to me, if something is a factor - then it matters. If Google looks to see if there are keywords on a page (or why would they even bother crawling right?) then it's a factor. Keyword density may be less important than it was back in the "wild west" of SEO but if Google looks for keywords on a page, then it counts - just less. Mark Metro Hi Speed.com