I don't completely agree that established playback singers should not participate in shows like Indian Idol. By that logic, one shouldn' t allow classical trained singers like Shravan and Rohit to compete against natural ones like Khudabaksh or Manya. That's kinda like saying star kids have it easier in Bollywood than an outsider looking to break in. Yes, perhaps getting the first big break maybe easier but only talent is going to let you ride ahead. And sometimes, being established may work against you. I know that I probably judge Revanth at a slightly higher standard (was not aware that Malvika, Tajinder etc has also sung playback) than the others, since I would expect his experience to enable him to perform better.
Same in the case of Shravan/ Rohit Vs Khudabaksh. I believe that training in classical does confer an edge over an untrained voice, but that's not to say that an untrained voice cannot be Indian Idol (the reverse is likely going to be true) Even if you look at yesteryear's playback singers..Mohd Rafi and Kishore Kumar, Kishoreda had had no professional training, but he rose to such heights of popularity because of his voice.
I think these days, everyone has a place in playback singing because of the genres of songs being composed, different voices are likely to be heard. Like we have Sonu Nigam and Shaan at the same time as Kailash Kher and Sukhvinder Singh.
Bollywood is a different ballgame than Tollywood and Revanth's experience may or may not have gotten him a break in Bollywood, but his appearing on Indian Idol certainly would. Same in the case of any of the other contestants. So yeah, what everyone keeps harping on that Indian Idol is a platform,,blah blah blah, seems to be true. Rohit got his break after someone heard him on Indian Idol, right? So why shouldn't others be given a chance to be heard by all of India (esp Bollywood) and get their ticket to fame?