The website title says "Arm Developer", not "ARM Developer", in a clearly non-acronym way so it's a guide for making prosthetic hardware. Of course you want a cyborg arm to parse JS natively, why else even get one?

Lie starts with L, dummy

Nope it's still a register-register op, that's very much load-store architecture.

It's reduced, not minimalist, otherwise every RISC CPU out there would only have one instruction like decrement and branch if nonzero. RISC-V would not have an extension mechanism. The instruction exists because it makes things faster because you don't have to do manual bit-fiddling over 10 instructions to achieve a thing already-existing ALU logic can do in a single cycle. A thing that isn't even javascript-specific (or terribly relevant to json), it's a specific float to int cast with specific rounding and overflow mode. Would it more palatable to your tastes if the CPU were to do macro-op fusion on 10(!) instructions to get the same result?

No, that's not what RISC is about. There was some early attempts to keep the number of instructions low--originally, ARM didn't have a multiply instruction, and there's still a bunch of microcontrollers you can buy that don't have a divide instruction--but it was quickly abandoned as it's just not that useful. It only holds back instructions that optimize common cases. Your compiler can implement multiplication by doing addition in a loop, but that's not very efficient.

What really worked about it was keeping a separation between how memory is accessed. You don't have an ADD instruction that can fetch from both registers or main memory. You have a MOV instruction that can fetch from memory into a register, and you have an ADD instruction that can work on registers.

ARM still does this just fine.