To add to that - Determining and defining what to build is not magic unless you write simple and elegant code that delivers on-time and on-budget.
You can have all the magic in the world upfront with planning and have it fail spectacularly without the right execution that is accurate, on-time and on-budget.
That's true. Until you realize that the accurate execution that was on time and on budget actually built something that didn't actuslly meet the business needs. Then what?
Yes. Execution matters. But it's only as good as understanding the target. Miss that target (read: meet biz needs) and no one will say "Yeah. But it was great execution."
True. I just see projects fail more often than not due to time/budget and/or shit code. Rarely do I see it fail because what was built didn't meet the business needs.
Although if you're in start-ups, they plan and then build terrible products all the time so the attention to upfront planning and the business needs is way more important in that realm.
You can have all the magic in the world upfront with planning and have it fail spectacularly without the right execution that is accurate, on-time and on-budget.