I don't see the separate DAC as a new fad, personally. Apart from my first CD player, a Sony CDP101, all my CD playing has been through a separate DAC, Sony 702ES, Meridian 606, Stax DAX(?), Spectral SDR 2000 Pro, Goldmund Mimesis 20. I have an Audiosynthesis DAC too with added custom 48kHz clock for my DAT recorder, dual dacs and balanced output which I used to use playing back my own recordings.
So as far as I am concerned it has always been a separate DAC, the only thing which has changed relatively recently is additions for computer audio such as 24/96 and 24/192 and USB inputs.
It looks like a new fashion for DSD has just started being marketed to convince us all to re-buy all our music and "need" a new DAC.
Cynic? Me?