I came here because I wanted to run some communities, but ultimately it was impossible on Reddit. All the names are taken, all the aging mod teams set in stone. You essentially have no meaningful opportunity to build anything new on there. In contrast, and especially with federation, the Fediverse is a completely different system. A fresh start - still after 2 years. And it has way better internal advertisement of communities than Reddit does.

And to be clear, on Reddit you can easily just shout into the wilderness at no-one. Big audience means you can get drowned out.