CDs, historically (especially pop and rock) have been mastered at higher and higher levels since their inception. It's really a terrible problem that is progressively degrading the state of quality recorded sound.

Chalk it up to idiotic direction from management at the labels and/or a contingent of folks producing albums that have no business doing so, and wouldn't have had the means to do so 15 years ago, if it weren't for the accessibility of technology today.