I think this is drawing the wrong conclusion. Humans can write assembly code too. The downside for a human is a greater time investment. For an AI agent, it's greater token usage. So, sure, you can get your agent to write assembly code directly, but just as for a human coder, all you're achieving is expending more resources for little or no benefit. You're burning tokens on problems (e.g. register allocation, stack manipulation) that can be solved more reliably with vastly less computation.