In the beginning, there was Red Hat Linux[1]. It was sold in boxes at stores such as CompUSA (remember?) but was also available for free download from Red Hat. Then, Red Hat decided they could make more money by spinning off Red Hat Linux into a separate enterprise-only product called Red Hat Enterprise Linux (RHEL), which they declined to make available for free in a ready-to-install binary form. Fedora[2] was also…
I wonder if they are also doing this so they can get an idea of who the user base of CentOS is and also try to convert them to paying customers.
Oracle Linux's distribution model is that you can take CentOS, change a couple repositories and make it Oracle Linux. Then if you want support, you can pay for it. With Red Hat, RHEL and CentOS before today were separate products with separate release schedules and separate userbases. This move gives Red Hat the opportunity to act more like Oracle Linux if they choose to.