It improves surface contact. That it works isn't a myth at all. Many people mistakenly put the blame on dust, thinking that blowing on it remove the dust which made it work.

It's not great for it in the long term, though, but hardly as damaging as much of the smug internet would want people to believe.

Nope. The problem was that the pins weren't seated properly. The solution to that is to take the cartridge out and put it back it.

Guess what happens as a side effect of blowing in the cartridge?