For now, we do what the web does, we have "Indexers" that crawls homeservers and serve trusting clients. I think that is a good pragmatic first step. On one hand it is cheap and simple, on the other hand there is no gatekeeping or walled garden, anyone can spin a crawler/indexer. All what signed data ever does, is enable altruistic sharing of the burden of crawling... but that assumes there will be that altruistic sharing in the first place... if it ever happened, fine we will help it.