The paradox in post is resolved by limiting the planning to Russian doll like nested timeframes and scopes, upgrading from endless 2 week sprints and quarterly or annual "planning" to cycles within cycles, scoped to human magnitudes of time, and JIT re-planned at the Nyquist interval of each cycle by those at the corresponding level of the enterprise org chart who must also be domain leads with mastery at that level and who have retained ability to probe two levels below while practiced at bringing along at least one level up.

The 1970 Royce paper was about how waterfall didn't work, and most "Agile" is a subset of DSDM, each flavor missing a necessary thing or two whether working in large systems or growing them greenfield from nothing. But DSDM wasn't "little a" agile (and SAFE just isn't). There is a middle way.

If you like applying this stuff (e.g. you've chatted with Gene Kim, follow Will Larsen, whatever, sure, but you've deliberately iterated your approach based on culture and outcome observability), feel free to drop me a note to user at Google's thing.