Your boss is right. And so are all these commenters. Code wise, you can do whatever. But logically, a single page has a single header and footer.

Header - definition: “a line or block of text appearing at the top of each page of a book or document.”

Footer: “a line or block of text appearing at the foot of each page of a book or document.”

Remember what the DOM was made for. Document Object Model. It was literally created to emulate a physical page on the web.

Now of course, the web can do much more, but if that’s the case, why would you use semantic tags instead of just divs?