True! I would find it more useful to just be able to lock an app into one side of the screen and have whatever the active window is just switch to the other side automatically.I feel that the limitations of Stage Manager (no coherent strategy for managing multiple stages) means that it is a less powerful way of managing windows than Split View, where I can easily manage multiple groups of windows, see those window groups and move between them.
Obviously I agree with everything else you said as well.