I've never quite understood, over 30 years of experience in software development, what problems Waterfall presented that warranted a complete refactor of software development processes such that things are now very much in cult-/cargo-cult territory. There is a natural process that every issue goes through: Analysis, Specifications, Requirement, Design .. then the Developer takes in the materials of each of these ste…
What do Developers do before it's a green light for them to start the dig? What do Designers do before it's "their step"? What do they do afterwards? What about those in preceding stages?
Well, they might as well do whatever else next that falls on their seats, but sure everyone still cares to see the "final output", that is the developed and tested product. Yet it's inevitable for them to switch their context to something else meanwhile.
And this detachment is what makes Waterfall process often protracted and resistant to change. Not speaking that there's also a Customer somewhere in that pipeline, hoping to derive some value and feed some form of input.
Some industries/companies/teams/products may be just ok with waterfall or no methodology at all. Other situations may want shorter cycle or even parallel efforts to stay in line with demand/constraints/risks.
Also, there's a "working software" factor too. Call it a PoC/proto/early demo... It not only tests the ideas, it also motivates to keep going or offers assurances that it will be done "right".
If anything natural there is to any process is that most professionals want to do their jobs well and be proud of their effort, preferrably rewarded for the success and not singled out for blame of failures.
The question is then how to create such an environment to make that possible.
Agile on not, what cargo-cults it is the general lack on internal vitality in some industries/companies/teams/products. And as such it affects the very professional values on all levels, eroding the collective "care" about the result or even the process itself.