The idea of brokers needing to keep supplier information secret to prevent a customer from going direct, has been a thing of the past since the internet came into play. Using anything from Google, to Alibaba, if someone needs to source an ingredient or material from anywhere in the word ,it's just a few keystrokes away.
Brokers play a significant role in the industry, providing service, product expertise, regional experience and product access that often cannot be obtained dealing directly with an original producer. Most organizations use brokers. Where there is a benefit from direct supply, the company will do it, regardless of a broker trying to hide their sources. A good broker, as noted above, that works as a partner with their customers, rarely has to worry about losing their business base so long as they provide a valued service.
In the US, FSMA, and in Canada, the SFC regulations, both throw in another complication - especially for imports - and verification of supply chain controls - which if you have no idea who the supplier is becomes a difficult position to try to justify.
if the broker has a complete supplier approval program, and their customers have verified the program, and regulations for that commodity do not require disclosure, it could work. Specific focus needs to go into the traceability and recall components of the brokers management system - otherwise you have to act on a worst case scenario - if there is a recall int he commodity you purchased, and have no idea who produced it, can you risk not assuming you're part of the recall?