I never owned a NES, but had a SNES and my brother also borrowed his friend’s Mega Drive (Genesis for those of you in the US) from time-to-time. All of us would blow the connectors on the cartridges, regardless of console. If anything went wrong with a game, the first step to troubleshoot was to take the cartridge out and give it a good blow.

It was never about how the console actually worked, a five year-old isn’t going to logically think about that. It was all about a perceived performance increase by doing it.