Does low power steering fluid (no leaks) damage the rack & pinion steering?

WHEN THE POWER STEERING FLUID IS REALLY LOW YOU WILL HEAR WHINING NOISE FROM THE POWER STEERING SYSTEM AND DAMAGE COULD BE DONE. FOR PREVENTIVE MAINTENANCE IT GOOD TO FLUSH THE POWER STEERING FLUID EVERY 50,000 MILES. GOOD FLUID HELPS THE SEALS IN THE POWER STEERING SYSTEM LAST LONGER. POWER STEERING REPAIRS USUALLY START AT $500 AND CAN GO UP TO $2000.HOPE THIS HELPS.THE $99 IS AVERAGE PRICE FOR THAT SERVICE.