I think (or at least I hope) that anyone who buys a support contract from a third-party company for a third-party distribution understands that they are not getting the same level of support that they would from Red Hat.

There is lots of room in the enterprise sector for third-party support. This is, for example, what almost all consultants effectively are. The third-party vendor can solve a lot of problems that the customer may not have the experience to deal with and can be well worth the price paid. But at the end of the day if there's an actual bug all the way upstream in RHEL, only RHEL can (permanently) fix that.

I've dealt with Red Hat in the past and one good thing about their support is that if you have a particularly thorny problem or a genuine bug, you will often eventually end up talking directly to someone who is either wrote the code or sits next to the person who did.