Are you sure you’re talking about the same thing as the OP? The feature request (which I wholeheartedly support) is just listing the communities of a specific instance, something that’s hopefully quite forward (since you’ll just have to ask an instance which communities it knows, no central directory required).
Thank you for the well thought out reply! I understand now that its not the way Lemmy devs envision this particular part of the fediverse to develop. It doesn’t completely agree with what I see in the current federation landscape though: Most communities cluster around shared interest, be they language, nsfw vs non-nsfw or ideology. Following that, there is a clustering effect regarding the communities on each instance: If I find an instance with a community I care about I’m pretty likely to be interested in the other communities on there too. My guess is: A popular app will implement this feature and it will become mandatory for everyone else who wants downloads. But I get the “idiomatic” argument and understand why Jerboa devs are unlikely to want this feature.