To an extent, you are correct in the original US NES design. However, time and analysis has shown that the loading mechanism is flawed. Due to the insert and push-down, there is no initial solid connection of the pins over the cart, as the tension on the pins does not exist until it is pushed down (think of it like a pair of pliers closing over the end of the cart when it is pushed down, but when it is open, the pins are not in contact). All previous, pin/cart connections (and future pin/cart connections), involved having the pins spring loaded so that the space between them was less than the width of the cart. When the cart is pushed into those pins, there is physical friction of the pins sliding across the contact points on the cart, mechanically cleaning the contact point (by pushing across it) removing dust and other light oxidation buildup on the contacts and pins. However, in the original US NES design, that physical cleaning does not occur as the pins never drag across the contacts of the cart, they simply pinch down on top/bottom of the cart as the cart is pressed down, compacting dust and debris onto both the contacts and the pins, making them progressively dirtier and dirtier over time. Even Nintendo's engineers realized the problem, which is why the NES 101 redesign went back to the old compression socket, as well as the SNES, and subsequent N64. The original NES pin connection was and is a design failure, all to make it seem different from past designs, stand out from the crowd of old consoles and make it appear to be like the high end tape players, and VCR's of the day (in the same way that curved TV's are attempting to look high end due to curved movie/theater screens which actually are high end because they resolve the fixed focal distance from a projector lens across a greater area of the screen).
This mod replaces the pin connector with a standard compression pin connector to make it as reliable as all other pin connectors. I mean seriously, I have systems that are older than the NES (Atari, Intellivision, TI-98a, etc) which still do not have any problem at all with their pin connectors and have never need replacement or cleaning (of both the carts or the connector), where-as with the NES, I have to polish my carts every 5-10 years and open and clean the pin connector in the console every few years as well to keep it working.