In the following blitz game played at ICC, Black just exchanged his f8 rook for the White Knight at f3. This type of sacrifice is about as common in the French Defense as the well-known exchange sacrifice at c3 in many Sicilians, especially the Dragon.
White captured at f3 with his g-pawn which weakens his pawn structure permanently and this more than justifies the loss of material. Material is, arguably, the most difficult aspect of a chess position to evaluate. So many weaker players rely too heavily on 5 points for a rook versus 3 points for a Knight or Bishop rule of thumb. This rule of thumb only gives partial insight into the value of the chess pieces. If chess were as simple as adding up points to determine the winner, it would not live up to its reputation as the most attractive and stimulating game in the known universe.
Maiming the pawn structure around your opponent’s King is always worth something. Master level USCF chess players usually know just how much it is worth in terms of what to sacrifice. Even the phrase “exchange sacrifice” can be misleading from a positional evaluation perspective. Often exchanging your Rook for a Horse or Prelate is just the correct move. Why attach the drama of a phrase like exchange sacrifice to the right move??!
Look up Miles Ardaman versus Joe Bradford for a chess game back in the 90s in Texas where Ardaman on the Black side of a Tarrasch Defense sacrificed the exchange fatally weakening Bradford’s King Side. I believe this was the only time Miles came out on top against Bradford whose hegemony of Texas Chess in those days remains unmatched to this day.