The most common reason for... «The Elements of User Experience»

The most common reason for the failure of a Web site is not technology. It’s not user experience either. Web sites most often fail
because—before the first line of code was written, the first pixel was pushed, or the first server was installed—nobody bothered to
answer two very basic questions:
. What do we want to get out of this product?
. What do our users want to get out of it?