Much like there was a "hop escalation" in IPAs, there's definitely been a "sour escalation" in coffee. It's fallen off a bit in recent years, but around 2012, it was bad (I'm looking at you, Intelligentsia!).

Roasters became accustomed to the sourness of the coffee, to make each new coffee taste "right", they had to make it more, and more sour. For those of us who didn't consume coffee in quite the volumes of the professionals, it didn't go over well.