There's a reason to review one piece of work at a time, but no reason to run only one agent at a time. Most “AI ships slop” takes are right about the slop and wrong about the cause: unsupervised AI ships slop, same as a junior nobody reviews.
Anti-AI is just anti-delegation with better PR. “If it can't one-shot it, I'll do it myself” is the same flinch a newly-promoted lead feels right before they learn to let go.
The best don't flinch. Running multiple agents at once and reviewing the output is what a staff engineer does having a team — shaping the code by shaping what's behind it, not by typing every line. You can generate in parallel, but you can only judge one thing at a time — and that single-threaded judgment is the whole job now. It's what we hire for, and it's who we place.