It's not a write, it's just a destination register. There isn't supposed to be some absolute number of instructions that a RISC has, the idea behind it is that

It's not a write, it's just a destination register. There isn't supposed to be some absolute number of instructions that a RISC has, the idea behind it is that you would take a quantitative approach to add instructions, and require that they show benefit beyond a composition of other instructions, and could be practically used. More capable compilers, wider use of vectorization and other techniques, and more transistors has pushed that a long way since the 1980s.