Why is the Salieri-Mozart relationship projected falsely in the movie Amadeus?

Question

Anselm Hüttenbrenner was a composer who studied with Salieri and it has been noted in Antonio Salieri and Viennese Opera and quoting him

Of Mozart, he always spoke with the most extraordinary respect. He, the incomparable one, came often to Salieri with the words: Dear Papa, give me some old scores from the Court Library. I would like to look through them with you. In so doing he often missed his lunch. One day I asked Salieri to show me where Mozart died, whereupon he led me to the Rauhensteingasse and pointed it out. It is marked, if I remember right, with a painting of the Virgin. Salieri visited him on the day before his death, and was one of the few who accompanied the corpse

Source of this quote: Anselm Hüttenbrenner, "Kleiner Beytrag zu Salieri's Biographie," AmZ 27 (1825): cols. 796-99; quoted in Rudolph Angermüller, Antonio Salieri: Sein Leben und seine weltlichen Werke unter besonderer Berücksichtigung seiner „großen“ Opern. 3 vols. Munich, 1971-74; 3:6; English translation in Thayer, Salieri, 177-78.*

Is there a specific reason why Salieri is projected as a character who despised Mozart?

Answer 1

The movie is an adaptation of Peter Shaffer's play of the same name, which suffers from the same criticism of historical accuracy.

I can't find any references to hand, but I imagine that Shaffer was using the historical setting to stage a story of artistic genius and professional rivalry that makes such a good story, and that accuracy was somewhat secondary. It is true that Salieri and Mozart were professional rivals, and that Mozart fairly obviously was the more successful - but it is also clear that their rivalry did not descend into hatred nor that Salieri had any part in Mozart's death, despite rumors.

On a positive front the movie makes it very clear that Salieri admires and respects Mozart's abilities, and you could argue that the movie is less about professional rivalry, than about Salieri's argument with God about his somewhat less stellar skills.