That's a terrific way of putting into words my thoughts about Stephenson, except I've thought of him as Thomas Pynchon for remedial readers rather than Vonnegut.
I don't remember AtD as being particularly filthy, but it has been a long time. It remains one of my all-time favorites. If nothing else, I'm indebted to the book for encouraging me to seek out literary westerns such as Warlock by Oakley Hall and Butcher's Crossing by John Williams.
It became a lot more enjoyable for me on my second attempt when I gave up on the idea of understanding everything. Sometimes things get explained later in the book. Sometimes not.