I use the sites all the time to query prices. I agree with the initial premise: 99% of the time, there is no reason to ever book using any of them. They yield a price that is exactly $5 and 1000 miles worse than the airline site.

But...I have used Orbitz twice. Once was to essentially build a multi-carrier triangle trip that I couldn't get any airline site to price for me. I tried splitting it up and booking pieces of it as one-ways, but Orbitz was the only one that could price all three segments on exactly the flights I needed for the lowest price. Yes, I might've been able to make phone calls, but it was on 2 airlines on which I hold no status, so it just wasn't worth waiting on hold to try and score 1k-2k FF miles.

The other time was when Orbitz had a fare that AA.com did not have. That has happened about 3 other times, and I've called AA Web Services and they've matched the fare. This time there was a hold to reach AA Web Services so I just took the Orbitz fare...

I have never had a similar experience with Expedia or Travelocity. Only Orbitz. Only time I hit the other two sites is when I'm looking for hotels.