Well, NFV is just another use case of OpenStack. There are many other use cases like application containers, hardware provisioning, object storage, Platform-as-a-Service, etc. It's fine to pick one and ignore the rest.
As for Amazon AWS, yes it's true they offer specialized services that are not available currently on OpenStack but most customers do not need these and can solve it in o
ther ways, for example the integrated MySQL database backend AWS offers. One could instead run a cluster of containers with clustred and loadbalanced MySQL or ProstgreSQL to do the same (and probably cheaper than the AWS service too).
I can count up to more than 50 different public cloud operators globaly running OpenStack. They may not be the size of AWS, GCE or Azure, but they exist and they offer the same services. Often for a better price for computing and network usage.