Why are auto-tuned singers (like Jay Sean, Miley Cyrus, and others) so popular? What happend to real singers?

I was looking at the Yahoo Top 10 Music Videos, and I watched a few seconds of all of them, and more than half of the Top 10 current singers used an obvious auto-tune program that warps (but tunes) the singers’ voices.

Why is this shit so popular now? And is this why these singers need to put on a visual “show” at their concerts?

And why are people that cannot sing getting fame for singing? The fact they need auto-tune is proof they cannot sing