Yes, you're right, but i guess no manufacturer will
build "it" in, and then later disable it in it's firmware,
(If it's not one and the same)
costs aspects i guess, but yes, you should ask this question,
because i guess downgrading the firmware in the drive is not
possible in most cases! only a new and hacked firmware can do this.
Also, CPRM is mostly used on the "minus" > -R -RW & -RAM media,
and it is "proposed" to be a feature of the ATA specs, so some of the features could be used on Hard-Disks, CPRM has always been a standard feature of the -RAM DVD media...