I hate to admit it but, In my experience, agile has brought productivity gains. When practiced correctly what agile seeks to do is, not skip the steps you ment

I hate to admit it but, In my experience, agile has brought productivity gains. When practiced correctly what agile seeks to do is, not skip the steps you mentioned from the traditional waterfall model, but to apply them iteratively to individual feature sets in sprints, versus across the entire project. I have seen many products fail to meet requirements and dramatically slip schedules under the waterfall approach. The project becomes too large and unwieldy, and too many assumptions are made that create dependencies for future features. The reason I hate to admit agile's success is because it comes at a cost--namely there are frequently externalities such as lack of documentation and developer burnout. Many agile implementations treat developers as cogs on a production line, responsible for essentially participating in automated CI/CD processes as a piece of software might be expected to do. And the relentless unending sprints can also easily take a toll.