I think of it as a continuum along the PDC, something like this:
Currently the TR WLs and PLs primarily exist in silos, or hard and fast lines like you said. A limitation to be aware of, and my guess is that it was better to launch Adaptive Training as-is, and evolve over time, rather than to continue waiting until its “more complete” or “moar better” because any product, and software in particular, can suffer from moving the goal posts and seemingly never launch. At some point its good enough to launch, and to solve a class of problems.
The current class of problems being solved is focused on picking the right workout, for workouts being completed in specific zones, within the context of a TR plan. Both for onboarding and ongoing, in order to improve ramp rate and workout consistency. Because ultimately it is about increasing volume, and you don’t want athletes blowing up or taking unexpected recovery.