Sure, and that works great if you have a small, motivated, experienced, and disciplined team with a deep understanding of customer needs. But that is not the reality in most real organizations that must reliably deliver software. They often need to get productive work out of inexperienced, undisciplined developers who don't personally know what the customers even want. So Scrum or something like it ends up being the least bad option that actually works.

You might argue that companies should hire more competent developers who fully understand the business domain issues. But there are few of those available at any price, especially in complex fields like healthcare.