From what I gather from a number of articles that’s in part what they were doing. The issue is they seem to have made a number of different contradictory statement as to their use of commercial chocolate and what for. Repackaging Valrhona chocolate with a few additions as their own, just repackaging it with no alteration, cutting their chocolate with Valrhona, and using Valrhona’s product for product development and testing, among other things. Its all pretty dodgy.
As for their marketing. Its always pissed me off. At a certain point they were implying that they were the only bean to bar manufacturer out there (not saying, just implying). Which makes no sense, because as you point out technically Hershey’s is bean to bar. As is every commercial producer including Valrhona. As for being the “first”. They weren’t even the first in NY. There were a bunch of craft chocolate producers in NYC at the time, including several bean to bar operations. Including Jacques Torres who opened his factory a full 3 years before the Mast Brothers turned up. I had a friend who staged with him for a brief period. He was scratch making chocolate in NY even before that, even if only experimentally. Most of these craft products were/are both cheaper and better than Mast’s stuff.
What the Mast brothers did was turn craft chocolate into a mainstream, mass market product. Primarily by glomming onto an already well established “Made in Brooklyn” aesthetic. Given that approach it makes sense that they would cut corners, and that their product would be both more expensive and less tasty than the competitors they’re emulating.