The entire point of the “fediverse” is to combat the network effect.

No, it's not.

The purpose of the fediverse is to decentralize control of the network, it does not eliminate network effects in any way shape or form. At the end of the day a social network is only as valuable as the users using it and contributing content to it. If they don't find lemmy pleasant to use, they're not going to say "let me jump to mastodon" they're going to go to Reddit.

Build one or wait for someone to build one you like.

You really don't understand network effects if you think you can just sit around and wait for basic functionality and expect your network not to die.