Why not? Its mostly a practicality.
The internet is designed to prevent corporations from cutting it up and making parts of it into islands. Which in the beginning they tried to do. Network hardware has to be made by someone, and very often that someone wishes to lock in their buyers to their own hardware. CISCO for example works very hard to gain customer lock-in. Because of this kind of business behavior, networks in the beginning were often unable to communicate if they were made by a different manufacturer. This became very difficult and expensive for people and businesses and governments who simply wanted to communicate. Therefore everyone began to turn to open standards defined by the IEEE assocation, which adopted the most open and most used and most fail-resistant standards. The internet is based upon a node-based system where each node can automatically redirect network packets if one of the nodes fails.
So its an open network. Your computer may send a packet of data anywhere. CISCO, Broadcom, AT&T, Verizon et all must all use the Internet networking format defined by the IEEE. If they want to participate.