Basically, this. In layman's terms: finding the good stuff on a decentralized network is hard, because not everybody or everything is all in one place. Some tools can help make the experience suck less, but it's a really hard problem that has lingered on for years.

This proposal is basically a team-up to develop the necessary plumbing so that services, such as search providers or distribution networks, can be easily used by anybody on the network, regardless of whether they're on Mastodon, Lemmy, or something else.

There's a few interesting applications here that go beyond just finding people, showing trending stuff, or providing an index of stuff. Some of this could be used for moderation tooling for admins, or custom feeds for users, or a directory of things to review. If the existing projects trying to solve all these problems came together, it might make a lot of things way easier.