I'm in the research and planning phase of a new website for a company that consists on 2 persons with different areas of expertise. I was thinking about designing a split layout inspired by this blueprint (a more robust and complete thing a whit a very different design overall) but I've noticed that a lot of websites that were using this sort of split layout changed their entire layouts and abandoned this whole split idea, which led me to thing that probably this wasn't working very well.
What I want to know is why doesn't this work for users? if that's the case. And, if not, what are the pros and cons of split screen layout for web pages?
Is it too unusual or unpractical for the average web user to understand it's navigation?