But let me try to express why people disagree. Change is software compared to physical systems is comparatively incredibly cheap. Unlike in building something known, design at the start of a software project is unlikely to be the one the client actually wanted nor would be the one that is one going to be build. Or at least it shouldn’t be.
The “brick-laying” part of software isn’t the hard part. Depending on want to analogise as “brick-laying” in software, that part could automated. Push to main and the deployment pipeline runs tests, makes sure things are working and voila! You have a new “house”. If its ugly or falls apart in software, easy , just revert to the previous version and its like nothing happened. Client wants a try different layout, it can be done affordably.
Most of the time in software engineering you don’t know exactly how to do something, there is always a degree of discovery, experimentation and learning involved. Heck the client probably isn’t expressing what they want clearly enough, and probably will at some point change their mind. Thus interacting with clients and customers is valuable.