It is hard to say without hard evidence, but in my opinion there is reason to believe this. It was also closer to how Sicilian mafia families were set up, would match the way colonies developed, and there are comments from Bonanno and Gentile about many more bosses attending national meetings early on (even if we use the term "boss" to include other family leaders). My research into Utica in particular gave me reason to suspect they were a small, separate family who later became part of Buffalo.
The US families at their peak were more like mandamenti in Sicily with the way they covered larger territories within a region. Sicilian mafia families don't typically control such a wide territory unless they are the seat of the capomandamento, which gives that family leadership over the whole territory. While the US didn't use the mandamento system, our idea of what a mafia family is in the US is much closer to that. On the other hand, there were a few US families that did operate more like Sicilian mafia families, being small and mostly centered in one city.
It would make sense that the early US groups would match the Sicilian model that created them, and that model is to have more groups of a smaller size. Leonardo Messina said the establishment of a family in Sicily requires ten members and these rules rarely change, so we can see where this would make it easy for small groups to be established, break apart, and/or be absorbed, especially at a time where there was more immigration, travel, and colonies came and went.
