It's hard to overstate the importance of the self recovery aspect of trainers. In addition to allowing the plane to "sort of" right itself, the stability also allows the pilot to take occasional breaks while flying. These breaks give the beginning pilot time to relax and gather their thoughts. Aerobatic planes that are lacking this characteristic in general take greater concentration, and require that the pilot control the plane at all times. Some beginners can handle this just fine, and for them starting with such a plane could be a good thing. For other beginners, this could be a disaster. Since it's nearly impossible to tell how the student is going to do before actually flying, a standard trainer is the safest choice. So, you're not wrong, there's just many people that it would not work for.