I'd be surprised if reselling through authorized sellers isn't much simpler and problem-free than selling them directly.

I also expect that using resellers ensures better odds of protecting the brand/project goodwill. Resellers deal with problems like "I paid a ton of cash for a board and it arrived late and/or broken". Support alone is a nightmare, and I recall that raspberry Pi struggled with PR when they started out. I vaguely recall Liz Upton being behind some ill-advised episodes that didn't improved Raspberry Pi's image and would get anyone other PR person sacked.