"Production-grade" typically means something that has been battle tested by users and has gone through all the trials and tribulations of dealing with their complains, suggestions, and other feedback to see an initial vision (the prototype) become what users actually want and need.

The earlier quote might be slightly overblown as some of those complaints, suggestions, and feedback can be iterated on more quickly thanks to AI. However, I think you will find that the overall premise is sound: The feedback loop is where you will spend the vast majority of your time and no coding agent can speed that up. Code was never the real bottleneck. A full-day coding session now being a 15 minute coding session helps, every so slightly, but when you still need to spend weeks talking to the users to figure out what needs to be done in that day/15 minutes, shaving off a handful of hours relative to weeks remains but a drop in the bucket. The marginal improvement is barely worth recognizing.