Copyright and classical music

Techdirt has an article about the effect of copyright on classical music. Classical music tends to straddle the time when copyright was invented, so there should be some good evidence for the value of copyright in achieving its aims of increasing the incentive to create cultural works. The latest research from Harvard, though, apparently shows the opposite.

For example,

as soon as copyright came into play, [Verdi] drastically slowed down his production of new works, since he could live off the royalties from older works instead