Search engines can actually rank a page for keywords that do not appear on a page. But, that does not mean you shouldn’t make it easier for them to understand what your pages are about.
Modern on-page SEO is not so much focused on keyword density as it is about making a page contain sensible keywords, related keywords, and a depth that shows the page deserves to be in the top ten.
So, you fail if you just cram keywords onto a crappy page.
And, you also fail if you do not add keywords, related keywords, and deepen your content.
Unless you are a major brand — who Google might give more leniency to — you need on-page optimization.
We have hired dozens, if not perhaps hundreds, of different writers since the 1990s to do on-page SEO. Some have had masters or doctoral degrees in writing. Some worked at the best traditional agencies. Others were doing it for leading brands or got good at it by being prolific bloggers.
One really interesting trend we found is that on-page SEO is widely misunderstood. People think it’s too easy or too hard. Some are cocky and say “I got this” and then are waaaay off of what should be done.
So, if you have any questions about getting this done properly, only hire someone who has a track record of doing EXACTLY on-page SEO. It doesn’t have to be us, but I share this out of a love for good SEO.
A blogger, ad agency writer, website writer, and certainly your programmer or designer may fail you and cost you lots of money if you assume they can do it right.