Only extremely old ARM CPUs (i.e. 32-bit CPUs from more than a decade ago) do not have AES hardware. All 64-bit ARM CPUs have it, like also at least the HW for SHA-1 and SHA-256. The more recent ARM CPUs have HW support for more cryptographic algorithms than the majority of the desktop CPUs.
"Lightweight" cryptography is not intended for something as powerful as a smartphone, but only for microcontrollers that are embedded in small appliances, e.g. sensors that transmit wirelessly the acquired data.
Not all 64-bit ARM CPUs have AES support since it's part of the optional Crypto extension. The BCM2837 in the Raspberry Pi 4 is an ARMv8 CPU that lacks it.
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.
"Lightweight" cryptography is not intended for something as powerful as a smartphone, but only for microcontrollers that are embedded in small appliances, e.g. sensors that transmit wirelessly the acquired data.