The downside of having encryption done on the CPU is that it has a max throughput and latency burden (even with AES acceleration) which isn't a problem for SATA devices (both HDD & SSD) but it is with new high-end NVMe drives that can see througput in excess of 1GB/s.
On the other hand, LUKS still has it's own attack methods when a volume is opened (cold->hot). If the keyfile/password is stored on a seperate drive or entered manually, the interface (USB keyboard, SATA connection, motherboard chipset, etc) could be exploited to retrieve the key in cleartext. If the key is stored or tied to the machines TPM, then it's up in the air as to wheter Intel/AMD + the motherboard's manufacture didn't leave a flaw somewhere. i.e How much more secure is the mobo/CPU TPM than the OPAL/ATA based encryption found on these drives?
Anyway, neither kernel fscrypt, nor dmcrypt have any dependency on drive embedded crypto. They do use AES-NI or equivalent, if available and if that support is compiled into the kernel.
Detail output from top while doing a scrub on a LUKS encrypted system. (Expires in 7 days.) https://paste.fedoraproject.org/paste/IvXs0f-N2~qN-k32Z2Y~yA...
dm-crypt (of which LUKS is a part) certainly does not do that.