When a carpenter starts working on your deck, you can immediately see if they are building what you wanted with the materials you ordered (the size, location, etc.) and you can correct the course early. It’s not as easy for software. You cannot really see if the programmer is building the correct thing before they submit their work for testing. In many cases it’s already too late. And the real test is when it’s released to customers. So, the feedback loop is much longer. I think that’s what they mean by “too late”.