Do You, or Have You Ever, Lived in the United States? Then You Are a Filthy Criminal.

[Reverend Joe]

Unless it's human beatbox music they usually bought some instruments, booked or bought a studio etc. to record that music, why is it wrong if they want something in return for those investments? So yeah, they do lose something material because they invested money to make that music in the first place.
And those who just make music because they love doing it and want to make people happy won't ask for money anyway and thus sharing their music is not illegal.

How many of the old bluesman or folk singers made any realistic amount of money by putting their music to record? None. And that's the way it should be. Musicians are supposed to make their money by actually performing their music to others, not recording a performance and sitting on their fat asses and waiting for the money to roll in. Making money off being a "studio band" is for people like the Beatles. Making money live is what real musicians do.