Some businesses produce and sell items on request as well as sell items in stock, and the items produced at request do not need to have their quantity tracked.

For example: A food truck produced burgers as ordered, and also sells bottled water and soda. It's beneficial to track the stock of the bottles, but they do not prepare meals in advanced and do not have a stock of prepared hamburgers to keep track of. The way the Inventory currently works, every time the merchant sells a burger, the burger quantity in the inventory ticks down further into the negatives.

You still want to be able to track the number of burgers sold, but you get no benefit out of tracking the quantity of burgers, and should be able to turn inventory tracking off for that item.