I'm by no means an expert on this, but I'll tell you what I think about the subject. Maybe someone else with more technical knowledge can correct me if I'm out of line.
HDMI cables carry several different signals on one physical cable, including multiple video carriers as well as sound. This is convenient for the consumer because you can replace multiple interconnect cables with just one cable. However, the quality of the cable does have some effect on the quality of the signal and also on the capacity and bandwidth of the signal. The lower the grade of cable, and the thinner the cable, the less capacity it has to keep the signal intact, and the more likely that the signal can degrade and possibly drop out before it reaches its destination. That is why for longer runs it is advisable to use a thicker gauge. Shielding helps to prevent interference from other electrical or magnetic sources, preventing the signal from being corrupted. Also, the terminators on the cable can degrade due to corrosion. A high quality gold connector is more resistant to oxidation and corrosion, which makes it more reliable over time.
Having said all that though, the Monster cables don't seem to perform any better than the much lower priced Monoprice or Bluejeans cables, although they might look prettier, and they may give you some kind of bragging rights.
When it comes to Monster, since the market is willing to pay it, then Monster is willing to collect it. Those that know the score don't contribute to Monster's coffers.