I don't agree with this. But it's an interesting take nonetheless:

I have long speculated that on-page optimization was trivial. It meshed with my understanding of how a suspicious Google engineer may treat the content of a page in relationship to its rankings. Why trust anything a webmaster says about his or her content (keywords stuffed into H1, meta, or bold tags)? Why trust anything on a page that a user won’t get to preview before visiting (anything outside the Title and Meta-Description, by-and-large)? However, despite my speculations, I lacked the data to truly start making conclusions about the usage of keywords in specific tags. Until now.....

The Triviality of On-Page HTML Tag Optimization