I suspect RRP/ MSRP have nearly always been useless. Comparison is the only way to get a true sense of what a regular market price is for something. Too often I will see something on a 50%+ off sale which might just be matching the market or actually 5-10% off where the rest of the market is at.

After all, why would a retailer ever discount more than 10-20% off what everyone else is charging, outside of a clearance?