Its Because Google Founders Sergey Brin and Larry Page didnt know html.
In the early days Google tested their newly made website on a few people.
The Test was based on how Normal people would react to the website.
There were tons of people simply looking at the Web page for 10's of minutes without even touching the mouse or the keyboard.
When asked by Google's engineers why they were sitting ideal?
They replied that they were waiting for the website to Load.
Google's design was so simplistic at that time,that even though the website had totally finished loading people were still waiting for it to load.
(The Google Story)By David Vise
Iv got a copy of the Book.