Occam’s Razor is a mental rule of thumb that instructs us to pick the simplest theory to explain something. A good case for this is “When you hear hoofbeats, think of horses not of zebras”.
Occam’s Razor is especially applicable to Search Engine Optimization (SEO) as people assume Google is doing some crazy artificial intelligence thing to rank one site over another, when quite often it is very obvious things like keyword usage on site that causes ranking differences.