I want you to consider instead the possibility that Waterfall came to exist, and continues to exist, for the convenience of managers: people whose methods are inherited from military and civil engineering, and who, more than anything else, need you to promise them something specific, and then deliver exactly what you promised them, when you promised you’d deliver it. There exists many a corner office whose occupant, if forced to choose, will take an absence of surprises over a substantive outcome.
I always have a hard time wrapping my mind around some of the classic user questions: What is this thing for, is it for novices or professionals, etc? I do my best to avoid these questions, because the best thing you can possibly accomplish as the maker of a tool is to build something that gets used in ways you didn’t anticipate. If you’re building a tool that gets used in exactly the ways that you wrote out on paper, you shot very low. You did something literal and obvious.
It is not evident, though many people, from the early Greeks on, implicitly act as if it were true, that all things, whatsoever they may be, can be put into words—you could talk about anything: the gods, truth, beauty, and justice. But if you consider what happens in a music concert, then it is obvious that what is transmitted to the audience cannot be put into words—if it could, then the composer and musicians would probably have used words. All the music critics to the contrary, what music communicates cannot (apparently) be put into words. Similarly, but to a lesser extent, for painting. Poetry is a curious field where words are used but the true content of the poem is not in the words!