It's more of a personal preference thing, and honestly it's somewhat unjustified.
But when I think about how long something will work for, I think about software updates. I don't care for the idea that at some day the amp will be fully functional... except the streamer. Not because the hardware failed, but because the streaming software is no longer being supported.
Similarly I think an ideal state would be to always have a standalone streamer. I don't even fully adhere to this with my CXNv2. And honestly I'll probably replace that at some point with another streamer/dac. But in the amp... I don't want it there.