Interesting that they are using Redhat 7.6 with a 3.3 kernel. I'm guessing RedHat must backport a bunch of stuff in order to make an older Linux release work well on such newer hardware.
It's actually ELRepo, which is community run, not EPEL, which is semi officially run by Red Hat. But yes, very impressive you can get latest stable and long term kernels on CentOS!