Great job on this article!  You mentioned [Up to but not including the 2018 edition of the IRC, the code prohibited]  “connect[ing] a food-grinding dishwasher….to a combination waste and vent system.  That might be stretching the intent of the code text a little too far. There is a big difference between the “macerating mechanism” within a very small fractional horsepower discharge pump (usually of plastic construction) that discharges through a small diameter corrugated hose versus a large fractional (or sometimes greater) horsepower disposer unit  with metal pivoting, spinning cutters that discharges through a 1-1/2 inch tubular waste pipe.  Most of the domestic dishwashers I have looked at have a screen in the bottom of the unit that would prevent too big of solid matter from entering the DW pump.