You replied to the very answer to your question. Apps can still be businesses, not everything has to be free. There's a bunch of free alternatives, this is just one of the paid ones.

They moved to lemmy because the fees on Reddit where exorbitant, and he'd have to raise the prices too much to keep same wage (Haven't looked at the numbers). Afterall, it's he's app, and he's to decide what wage he wants to keep working on it.