The suits ought to learn a thing or two from Ric, but they won’t bother listening to the grassroots from their high towers.
Who are the 'suits'??
Why would you buy a DAC, a preamp, analog interconnects and a regular class D or other amp......when all of that can maybe be replaced by one component?
Presumably if the amp you're using only accepts a bit stream as an input then this question is very easy to answer!
You would keep the DAC separate from the amplifier for the simple reason that DACs have been under continuous improvement over the last 40 years and many of them have decent volume controls in them these days so a preamp might not be needed. Of course, class D amps have seen vast improvement in the last 50+ years too!
So if you wanted to upgrade your system by getting an improved DAC or amplifier, you wouldn't have to replace the whole thing.