Several of us need Analog to Digital converters in addition to a high quality DAC for playback of digital sources.
jp# does needle drops of vinyl and if you want to use digital signal analysis software, you need a way to convert audio and analog sources to get them into your computer.
Me, I have a pretty sophisticated home studio.
I started doing live music editing, a little mixing, post production and now I concentrate on music production of my own works.
It's a real golden age for guys that do stuff like me .
I got my first Metric Halo interface (ULN-2) way back in 2009 IIRC. I've updated it once and I still use it for location recordings.
I bought Voltron's Amarra (LIO-8) a few years ago, added 4 mic preamps and then upgraded it to 3D about a year ago.
Each of these upgrades were like getting a new updated interface with improved sound and more modern connections.