Yes and no....That is the newcomers get a chance to be seen by millions but in the end the show is about ratings. The young dancer on America's Got Talent, for instance, said aloud what most already knew:
He was not in control of his own performance. The shows drop people, bring them back. eliminate others, all in the name of ratings....They're NOT on the air for altruistic reasons, it's all about the bottom line.
That being said.... the talent is exposed to a huge audience they may not otherwise reach. Agents and promoters watch these shows, I imagine, and are probably there at auditions too, trying to sign new acts so as to earn their 10%. If the people do have a bankable talent you can bet somebody will sign them and they'll get their shot.
So, yes and no, the shows may not promote talent the way they tout, but talent gets promoted anyway because of the exposure.
Just the way I see it..................JT