The cold facts of the matter are these.
Those who partake in these talent contests lack the love of music and/or determination to succeed and make a name for themselves. Instead, they rely on a TV show that is pretty much a guaranteed money maker for the winner, only to wind up making Z-List celeb appearances in clubs and TV shows 12 months down the line. Again, with the exeption of Girls Aloud whose string of hits speak for themselves, but where is Gareth Gates, Michelle McManus, Chico, Steve Brookstein, Leon Jackson etc. now?
They may have the voice to get through a televised TV show, which is ridiculous at times anyway given how far the 'Twins' got, but generally, they don't have what it takes to progress in the business.
Leona is looking like she may be the next to build on the starting steps, but we'll see.