People have suggested making a portal/quiz for instance signups, but that adds to the barrier. There are also problems like how in-depth and inclusive it should be. It reminds me of Linux distro pickers that often suggest weird niche distros.
There are already big/default instances in the Fediverse though but there are people who actively discourage this. Maybe Mastodon just had a bad start and Bluesky learned from that. I wonder if Bluesky’s PDS will be like Fediverse instances though. Many Fediverse instances are built around shared interests but the PDS just looks like a glorified handle.
Personally, I think the Fediverse discourse should shift to designing social media with decentralization in mind rather than mimicking mainstream social media with a “decentralized twist”. I don’t think the Fediverse will ever be as big as Twitter, but it doesn’t have to be. It just needs to be sustainable enough to keep new conversations going.
Doesn’t answer the question but maybe it’s worth sharing anyway.