There are some situations in chess where a pawn push in the center is the most played move, and also the one suggested by engines. However this is not done for winning material, but just for trading pawns. One such example arises from the Philidor Defense:

```
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
1. e4 e5 2. Nf3 d6 3. d4 exd4 4. Nxd4 Nf6 5. Nc3

```

`3. d4` is the move I'm talking about, and the game after that move usually continues like in the PGN above.  

I don't fully understand the advantages that White gains by exchanging its *d*-pawn for Black's *e*-pawn, ending in the position shown above. They are both central pawns controlling central squares. Can someone tell me some insight or considerations I'm probably missing?