but the greast importance of System 2 comes at the edges of the envelope and emergencies. In AF447 or Pinnacle 3701, where there was no excess thrust
These are not examples of the edge of envelope but well beyond it. You don't follow a procedure of stall recovery for normal approach. Whenever one is tracking a flight path it is maintained by pitch and speed managed by thrust. It's straight forward. When thrust is constant whether at idle or climb you are not tracking a flight path but maintaining a certain speed so obviously it has to be maintained by pitch.