Redhat has really clever model, btw. Once, in times of RHEL3 and 4 they have tried to maintain zillion patches against vanilla kernel to be "Enterprise Linux",

Redhat has really clever model, btw. Once, in times of RHEL3 and 4 they have tried to maintain zillion patches against vanilla kernel to be "Enterprise Linux", you know, so you could run Oracle cheap (a hot topic in that time). Then they have realized, that it is much smarter to give the patches to the mainstream, so everyone will benefit. Fedora became a test-bed for a new technologies, to amortize the too rapid changes (systemd and other crap, you know), so they could provide stable and compatible RHEL versions for existing customers. And Redhat is a service, not the code company.