Beer and liquor wholesalers are excluded deliberately. Chicago has a large alcohol distribution trade, and some of those companies do carry non-alcoholic lines, but they operate inside the three-tier licensing regime, which means an operator cannot simply open a non-alcoholic account with one the way they would with a coffee roaster. Putting them on a restaurant-supply page would imply an option that is not really available. The reasoning, in both directions, is recorded in our research notes.
The other absence is the big one: the national bottlers. Coca-Cola, Pepsi and Keurig Dr Pepper are not independent distributors and are not what this directory lists, but they are who most Chicago operators actually buy fountain and packaged drinks from. This page is the independent alternative to them, and for fountain specifically that alternative is thin.
One more thing we could not resolve and will not guess about: two roasters on this page, Big Shoulders and Halfwit, publish the same street address in Pilsen, and neither mentions the other. There is presumably a shared roasting facility or a history behind it. We could not verify what, so both listings carry the address and neither carries an explanation.