Why OSPF and not ...

BGP
no auto-configuration
slower failover (in theory)
used as external gateway protocol (EGP)
RIP
everything is better than RIP
slow
does not scale
count to infinity issues
IS-IS
ITU approved standard made by IBM
nobody groks the standard
EIGRP
Cizzzcoeee tuned RIP
no documentation, not open in any kind
even worse then RIP