Congrats! You just rediscovered something called water-fall model.
The bad rep comes from (defense|gov.) contracting, where PRDs where connected to money and CR were expensive, see http://www.bawiki.com/wiki/Waterfall.html for better details.
But I expect the AI zealots to start (re-)integrating XProgramming (later rebranded as Agile) back into their workflow, somehow.
A waterfall model with short feedback loops iterating on small tasks is not the worst thing in the world
The problem with "AI zealots" is seldom that they spend too much time planning ahead. If anything, it's the opposite.
Agile is a set of four principles for software development.
Scrum is the two-week development window thing, but Scrum doesn't mandate a two week _release_ window, it mandates a two week cadence of planning and progress review with a focus on doing small chunks of achievable work rather than mega-projects.
Scrum prefers lots of one-to-three day projects generally, I've yet to see training on Scrum that does not warn off of repeatedly picking up two-week jobs. If that's been your experience, you should review how you can break work down more to get to "done" on bits of it faster.
All that said, in most orgs I've worked with, they were following agile processes over agile principles - effectively a waterfall with a scrum-master and dailies.
This is not to diss the idea of agile, just an observation that most good ideas, once through the business process MBA grinder, end up feeling quite different.
In my experience, they're all waterfall in scrum skin, except they also lose the one thing that was a strength of the old-school method: building up a large, well thought out, thoroughly checked spec up front.
So in the end, "business process MBA grinder" reshapes any idea to adapt to leadership needs - and so here, Agile became all about the things that make software people predictable cogs in the larger corporate planning machine. They got what they need anyway, but we threw away the bits that were useful to us.
Twelve :-) Twelve principles and four values