Web site design seems to go in fashions. About 12 months ago the “Metro Look” was all the rage due to Windows 8. The latest trend is to have extremely long pages that have everything on the home page with navigation that moves you to specific section of the page.
The trouble with these long pages is that Google can get confused as to what the page is all about. If you moosh together company purpose, company history, product details, testimonials and contact details all on one page you can understand why Google could get a little confused.
One of the golden rules of SEO is to make it crystal clear to Google what the page is talking about and where possible, dedicate one page per search term.