Since time immemorial, producers and artists have been pushing mastering engineers to increase the loudness of audio.  The nonstop march of technology has been making it possible to do this.  But why?  Well, to get your attention.  Listen to the radio, and the song that grabs you out of your drive-time zombie haze is the loudest one.  Watching TV, the loud commercials certainly get your attention (So much so there are now international standards to combat that).  On a 3-minute pop song, it’s fine.  When it’s all you hear?  Fatiguing in the extreme.