My very first over-the-board game many years back started with the QGA and went the way of the first line shown.
I was playing a kid rated 1900 so I was expecting 100 moves of theory. After the game he told me he'd never seen the Queen's Gambit before, so tried to play it like the King's Gambit (how can you get to 1900 and never see a Queen's Gambit?)
After Qf3 he was a bit disappointed. He played Nc6 so that he lost a knight instead of a rook. Then he started a hugely complex sequence of moves... and lost a bishop and then the exchange.
Someone said the reason moves like Qf3 work is that you are moving the queen in one direction to attack in another and people don't expect that.
Maybe he meant he had never played 1...d5 before and was a KID , Nimzo or Benoni
1...Nf6 player. Going by it's very high success rate, it has by far more victims than any
other opening trap, I think it's the harmless looking 3.e3 and you only see Qf3 being
played in 1.e4.e5 openings by players looking for Scholars Mate so it does not register
as a possible threat. You do not expect to be losing a piece in four moves so your
sense of danger is not on full alert.