I agree with you that especially when you go deep or reach a level like rescue you need to be a bit independent.I haven't studied this very problem thoroughly, so you might be correct.
... about the orthogonality
Maybe I demand too much.
But for example, if you do SDI solo diver there are a few things that aren’t taught so much in a rescue class:
- make sure someone knows where you dive if you solo dive, when you’ll be in the water and out of the water and preferably when they should call emergencies if they don’t see you (this is for example not obvious for a shore dive)
- carry redundant cutting tools that are accessible easily
- backup torches, DSMB and mask
The emphasis is more about starting the dive alone without a buddy.
I agree, that ideally, at some point a diver should be self-reliant though.