Lemmy is not supposed to replace reddit. Lemmy is it’s own thing that has already existed for years now. The benefit of Lemmy over individual forums is the interconnectivity of separate communities and being able to view content from multiple communities in one single feed. You can subscribe to communities and view all your subscribed community posts in one feed. Theres also the All sort on the main page, which essentially functions as Lemmy front page. Its also, as you said, not centrally controlled. So if one part fails the rest can continue as normal. That makes it pretty robust. But it isn’t meant to replace reddit, a massive social media platform with millions of users.