Without Harnoncourt, we wouldn’t have had this: Dorothea Röschmann (Vitellia) and Vesselina Kasarova (Sesto) in Mozart’s “La clemenza di Tito”, Salzburg 2003, conducted by Nikolaus Harnoncourt.
Without Harnoncourt, we would listen to Early Music differently than we do, mainly because it would be played differently.
We would have much less Early Music to listen to in the first place, because Harnoncourt was central to the early days of Historically Informed Performance Practice, and a tireless champion of Baroque music.
We have been talking a lot about Baroque rhetorics in the last few days: he was one of the people who promoted thinking about it in a pre-romantic manner. Perhaps others with less privilege remain unjustly unnamed, but that does not take away from the fact that he was important in making Early Music be heard again, and be considered from a historical perspective.