You are right but only some patients are candidates for the repair-versus-remove option. Studies show that the long-term result of complete meniscectomy is osteoarthritis of the joint.
Without the cartilage to act as a shock absorber and protector of the joint, degenerative changes speed up. That's why surgeons are trying to repair the torn meniscus instead of taking it out.
Meniscal tears are more likely to be repaired when healing can occur after surgery. The tear must be located in an area that has good blood flow. Most of the meniscus doesn't have a blood supply. Only the outer one-third edge of the meniscus is in a zone that has blood vessels.
Small tears in this area are the most likely to heal after surgical repair. The damage must be fairly minimal without degenerative changes. Usually the torn meniscus has occurred as a result of trauma in a young patient.
Middle-aged adults are more likely to have meniscal changes and tears because of the aging process. Degenerative changes of this kind are removed as you described. The surgeon will still preserve as much of the remaining healthy tissue as possible to prevent further changes in the joint.