This happened in ALL youth ministries including sports. The Church sought to become political and pursue mercenary interests. The amount of money it took to support an ongoing youth program was not large. In those days, the economics was very different. A corps could take a parade for $150 and the bus only cost $40 to 50. Likewise contest money. A corps could break even even with poor contest results. But the fees for contracted services with any municipality were far greater and much more appealing to Church leaders.
The dumping of youth onto the streets contributed to a rise in crime that slowly took off at this time in places large and small. There was no other organized outlet for such large numbers of youth and instructors. This also had a severe cost in depriving emerging talent from guided development from qualified and dedicated instructors. It killed dreams and careers.
It also began the process of weakening the family unit which was being held together by the support and interest of parents, siblings, relatives and the general community for the corps and sports teams. It put a burden on families and parishes with no interest in the consequences of the Church's decision or supplying an acceptable alternative replacement. The parishes sold all equipment for the most they could get, wiping out the memories and pride of achievements. All this equipment was fully depreciated. It could have been placed with other organizations that could have continued the corps and teams but the lure of the buck had a greater appeal. The Church had no social conscience.
This activity kept people's children trapped into very limited futures and control of the Church. It was all done, like my friends Frank and John said above, for financial reasons. The missing point has been the Council of Bishops' decision and orders to their parishes.