Because of the federated nature of the platform, discoverability is not easy, making it more difficult for brands to be discovered by potential followers. There are also no algorithms at play to help content go viral like on other social networks, as content is just served chronologically, which might also be a limiting factor to reaching potential audiences. Finally, as Mastodon doesn't have an ads business, you also can't reach your customers in that way. All these things make it difficult for any brand to achieve easy success on the platform. However for the brands that do make the move, they can use the first-mover advantage to help build an audience.