“SEO”

The term "SEO" is beginning to piss me off. A client's "SEO guy" recently suggested that my web developing skills are below par, because "I use <p> tags, which search engines don't highly rank. [....blah blah blah....] and it's best to put content in <h4> tags". Honestly? I asked him to source that, but I never did get a response. I suppose I just never knew that headings and paragraphs were the same thing.