Because the competitive landscape of the web is such that the site which looks and works best gets the most traffic, developers and designers put a premium on the presentation of that content and let structural markup take a back seat.
Because parents have power over children. They feel they have to do what their parents say. But the love of money is the root of all evil. And this is a sweet child. And to see him turn like this, this isn't him. This is not him.

