Anything lined with neoprene will help - studdies show that neoprene helps in absorbing shock - but it is not the 100% way to preserve our horses legs.
But your dad is right in a way. A horse has only so much jump in them, and their legs take ALOT of shock and trauma when they jump. Take a 1200lb horses body weight all compressed on their shouldres, knees, cannon bone, ankles, hooves.
Studdies have shown that our horses legs take alot. Many Top Level Jumpers know this, so they focus alot of proper conditioning and Dressage training, so that their horses are stronger and conditioned to do the sport they are being asked to do.
They spend 5 - 6 days a week doing Dressage and preserve their horses legs by jumping once to twice a week - if not only at the comp in the warmup ring.
Prevent
Protect
Preserve