To an extent, influencers wouldn't get on with Mastodon anyway.
Looking at it charitably from their point of view, the discovery is so poor that actually building a following there is a huge amount of work they probably won't see a return on. It's a much smaller audience that in no small part resents even the idea of an "influencer" - someone who has that as their line of work is going to struggle and consider it not worth their time.
Looking at it less charitably, Mastodon does not reward activity on its own but instead things only get attention if they're actually worth attention, so carpet-bombing fedi with posts most people don't actually value is a waste of their time, and it's a lot more effort than such people would typically be willing to expend.