Nostr is a distributed system. That takes some serious sysadmin'ing to keep popular services up that go against the distributed nature of nostr (like indexing or search). The service was too popular, everyone used it, then it died because (I assume) it doesn't have the time or money to keep it alive. These are the things that slow down growth because we become dependent on things that are inherently unstable and have no mechanism to account for time or funding being spent. When you recommend a service or utilize a service in your apps, keep this in mind. Don't use or become a central point of failure.