Yes. I worked at a site that had an SEO-obsessed boss and basically the keywords, placement of keywords, formatting of the page, everything...all affected SEO.
However, that all likely paled in comparison to him gaming the system by paying to host separate sites that linked back to his in an effort to boost legitimacy during the times when SEO was a make or break thing.
It's definitely an arms race. Sort of like tax avoidance. As long as you have search engines ordering results, I guess you'll have people who seek to game the results. The question for me is whether what Google does can be improved upon. I think we can do much better.
That only covers backlinks and authority, it's just one piece of the puzzle. Ironically, that's called a "black-hat" way of obtaining backlinks and authority. The "white-hat" way is to go to legit websites and purchase links, literally pay them to link your website. This is a great example of what's considered "ethical" in SEO
However, that all likely paled in comparison to him gaming the system by paying to host separate sites that linked back to his in an effort to boost legitimacy during the times when SEO was a make or break thing.