Bob Dylan and Freddie Mercury came across as authentic, that’s why.
Because they are. Dylan's a massively talented lyricist who goes where his art takes him - no f*ckin' around. Mercury was a phenomenal singer/songwriter and by all measures a down-to-earth, generous guy.
On the other hand, Springsteen's a total put-on; a fake, a leftwing rumpswabber and a fraud whose handlers tried many different looks to get him to "stick." They hit pay-dirt with the fake working class hero, jeans and tee shirt angle. Someone once said that he should sing about the things he knows, like yachts, fashion models, rich people and drug-fueled parties, not about the woes of the working class, which he has never experienced.
When I hear a Springsteen song come on the radio I lunge for the volume knob and spin it down to -11.