I notice this too, but it seems to fly in the face of a lot of people who say "make the page short , people don't want to read".

Case in point a lot of startup websites that have one sentence of huge text saying "X let's you do Y with Z" and then a gigantic "SIGN UP" button and nothing else on the page.

There's also a lot of pages that seem to do a halfway house and provide a lot of images for re-enforcement. Like this one: http://www.apple.com/uk/ipad-mini/overview/