All of these methodologies (and most formal software architectures as well) have as a their main sales pitch the idea that you can hire average/entry-level developers and build good software with reduced defects and on a defined schedule if you only follow these magic guidelines.
It refuses to learn from The Mythical Man-Month and recognize that building software has an essential complexity that cannot be avoided. You need smart people to implement and manage it, and you'll have to pay them what the market says they are worth.
Building software that's more complicated than a standalone CRUD system is hard, it will always be hard, and unpredictable, and to some degree stressful. No methodology will ever make it anything else because the methodology used doesn't change the nature of the problem.
It refuses to learn from The Mythical Man-Month and recognize that building software has an essential complexity that cannot be avoided. You need smart people to implement and manage it, and you'll have to pay them what the market says they are worth.
Building software that's more complicated than a standalone CRUD system is hard, it will always be hard, and unpredictable, and to some degree stressful. No methodology will ever make it anything else because the methodology used doesn't change the nature of the problem.