[TomVDB]

The RISC-V compressed instructions are more a shorthand for some commonly used 32-bit instructions than a 16-bit ISA that stands on its own: the compressed instructions lack a number of essential operations that make it impractical to only use compressed instructions

This is in contrast to, say, the ARM Thumb instructions, where you can can have entirely libraries that use 16-bit instruction without ever needing a 32-bit one.