I recently learned that this is a valid way for White to play for advantage against the Philidor:
[FEN ""] 1.e4 e5 2.Nf3 d6 3.d4 exd4 4.Qxd4 Nc6 5.Bb5 Bd7 6.Bxc6 Bxc6
According to the Lichess database, White has won 59% of games from this position, while Black has only won 34%. The Masters database also heavily favors White, with 31% White wins / 17% Black wins.
What are the ideas behind White's 4.Qxd4 move, and why does it have such a high winrate? What is White's motivation for violating principles like bringing out his queen very early / giving up the bishop pair?