Still, that's irrelevant because mobility is one of the main purposes of the fediverse. That is, move to Lemmy or something else like kbin, yet, you're connected and may move again later on. Transferring of one's own content is still an open issue, though.
Besides, while tildes incorporates a lot of the lessons mods learned already after the first half a dozen years of Reddit, it is not meant to scale. It's a platform for small/medium instances, not very large ones.
It's a pity, though, there is so little support for decentralization/federation just because its design is a bigger challenge. Another reason is, however, the absence of a constitutional protection of one's privacy outside one's own property. Because of that the consumers of the dominating nation in that market don't really grasp nor care about that aspect.