Another is the 3ware 8000 series. We got a dead machine in recently for repair and were faced with either moving the RAID drives and card over to a new server chassis while being restricted to the EOL'd CentOS 5 or upgrading to CentOS 7 but being forced to buy a 9000 series card and rebuild the array.
Lose-lose.
Well, I can see why Red Hat wouldn't want to support those old cards forever. Including the driver would be easy, but actually supporting it (QA, support...) is not.
They already supported them for close to 10 years, which is much longer than most hardware lifecycles last nowadays (3-5 years).
You could still build a custom kernel but yeah.
The card in my home server is an Intel SASUC8I reflashed with IT firmware, so it's equivalent to an LSI SAS1068E. The driver for that is listed as "deprecated" in 7.