Writing sensible HTML is optimising for machines. The Google algorithm runs on machines, so they'll like it and benefit from it. Browsers, screen-reader, future colleagues will also like it and benefit from it. Calling this search engine optimisation seems a bit weird, though it'll certainly help Google process your website properly.

If you read the OP, his mean concern is the tiny subtle changes in the algorithm that drive him mad. He calls optimising for them SEO. It is considered shady and evil by some, myself included. (Ultimately it's about the content, not about who best reverse-engineered Google's algorithm.)