What about the people that go to work or travel that want to strap it to their pmp on the train/plane/ car and then plug it into their laptop at the destination? It isnt useless for everyone. There is a reason it is so popular.
I personally use portable units as portable units like you. But a few times have come where a dac played in handy
I was moreso speaking from a personal perspective, but you're right, I hadn't considered that. But I have now, and I still can't see me getting a DAC/amp portable.