You are right that the cryptographic instructions are optional and they have always been so in ARM CPUs, in order to enable the making of CPUs that can be embedded in products that will be exported even to destinations where cryptography is forbidden.

However the poster above was talking about smartphone Arm-based CPUs. I doubt that there has ever existed a 64-bit ARM-based CPU for smartphones that did not implement the cryptography extension. Even the CPUs having only Cortex-A53 cores that I am aware of, made by some Chinese companies for extremely cheap mobile phones, had this extension.