Since the airline's inception in June 1971, an inop anti-skid was deferral was possible under the MEL. They didn't fail and get deferred all that often, but when they did, and it couldn't be repaired, the MEL relief was utilized, the performance penalties and various MEL-mandated provisos complied with, and off the aircraft went until it could be routed into MX.
All that changed post-incident. Although relief still exists in the MMEL, we've gone more restrictive and it's no longer deferrable.