Kid Rock's success sans iTunes apparently prompted Atlantic Records, owned by Warner Music Group, to pull an album by R&B artist Estelle from iTunes, too (Estelle's album remains on Amazon's MP3 store, but is sold "album-only").
AC/DC has never put its music on iTunes either, the WSJ points out, and still managed to enjoy some success with 2.7 million CD sales last year.
And, of course, Jay-Z made headlines late last year for boycotting iTunes when his new album (at the time) American Gangster went on sale. "As movies are not sold scene by scene, this collection will not be sold as individual singles," he said at the time. The one thing we'll likely never know, though, is how much more successful these artists would be with the help of iTunes, if at all.
These artists' complaints aren't so much iTunes' fault as they are the "fault" of the evolving music market. There's an endless supply of other music stores that also sell music on a track-by-track basis, because customers just plain love being able to cherry-pick their favorite songs. Digital downloads just make that easier, but the practice itself has been around for decades.