It's not a new fashion. In the 70s/80s hifi often had a "loudness" button which boosted highs and lows, although not as much as they're boosted by EQ settings today.

The more recent variant is "smiley curve" EQ - high at the extremes, drooping in the middle.

EQ can mess with transients, especially in the bass. You get more volume, but at the expense of some time smearing.