1. This sounds great in theory. In theory there is no difference between theory and practice, but in practice there is.

2. I would be more receptive to this argument if they had listed some famous examples of successful, large systems that were built like this. On the other hand, I can easily list many failures: FAA Advanced Automation System (1980s), IRS Tax Systems Modernization (1990s), UK NHS National Programme for IT (2000s).

3. Waterfall vs. agile is a continuum. Nobody plans everything, down to each if-statement, and nobody wings it without some kind of planned architecture (even if just inside one person's head). Where you are on the continuum depends on the nature of the problem (are all requirements known?), the nature of the team (have they done this before?), and the criteria for success (are there lives depending on this?).

4. The analogy to building a building is flawed. At large enough scale, software is like a city, and all successful cities have gradually evolved in complexity. Come back to me when someone builds a 1-million person arcology on some island in the Pacific.

5. Just as some PhDs are sensitive about being called "Doctor", some software engineers are sensitive about being "real engineers". Stop thinking about that. What we do as software engineers is immensely valuable and literally changing the world (usually, but not always, for the better). Let's stop worrying about whether or not what we do is "engineering" and focus on what we do best: building complex systems that have never before existed on earth.