Look at what Ilford did before they went bankrupt.
They sold OEM film to places like Freestyle and Fine Art Photo Supply, and probably many others. While volume can be good in terms of market share, if you make little to no profit on each sale (especially since people quickly figure out they could buy FP4+ for very little money), then you quickly eat into the total profitability of the company. Every sale must count.
Now that they are a healthy and sustainable company, they don't use their own emulsions for OEM purposes anymore.
I can't say that I blame Fuji for not supplying OEM films anymore. In pure economic terms, profit is better than volume.