> In my experience, letting the agent make every decision leads to a big ball of mud that requires touching dozens of files to make a change

It seems too early to make any conclusion like that. We've still only been doing agentic coding for a year and capability significantly improved during that time. I don't think anybody on either side of this debate can have actual empirical evidence to support conclusions about where it lands longer term.

The main argument I see is that it probably pays to be slightly conservative because the cost of being wrong by maintaining too much oversight and shipping slightly less code is better than the cost of ending up with an entirely unmaintainable system. In some cases it will be more than "slightly less" but in almost all complex pre-existing systems, you are rate limited by a lot of other factors outside of code production, so the effective difference just isn't that high.

At agentic coding velocity, tech debt becomes obvious much more quickly. Empirical evidence is a bit of a ridiculous bar to hold for software development - we are as quantitatively blind now as we have ever been - but at least for me the anecdotal evidence is very clear. Today's agents hill-climb and their software architecture is pretty reliably bad without a human in the loop.

And it's debatable how much better they will get quickly. Verifiable rewards for maintainability of software is, I think, possible but very hard.

When I said "in my experience" I meant literally that, my experience so far. I'm not making any predictions. I'm definitely anticipating things improving at a rapid pace, which is why I think it's good to run frequent experiments. If in a month I find that an agent can one-shot a 20k line project without creating an unreadable, unmaintainable mess, that will be great.