By all means, feel free to design your own ISA to fit every use case from the get-go, publish it in its final state, port toolchains and relevant software, and

By all means, feel free to design your own ISA to fit every use case from the get-go, publish it in its final state, port toolchains and relevant software, and convince the world to use it. RISC-V chose a different approach, because this one, quite frankly, would not have worked.