Not sure if this will help. It's a searchable list of communities sorted by newest created community. Refreshes daily. https://lemmyfind.quex.cc/

It's worth pointing out that DNS servers are not federated. There is a central master list that all other DNS servers replicate. This authoritative list is a single point of failure, particularly with regard to censorship.

The idea of developing a community discovery protocol as a subset of ActivityPub is a really good idea. Something similar to DNS could work but the problem lies in that DNS is fairly centralized and controlled. Look at what we have now with the political shit show that DNS has become. I think a whole new protocol would have to be developed to facilitate this. A community discovery protocol might share community lists between instances in a federated way for example - maybe much in the same way that ban lists are federated.

Let's say every lemmy instance has a "memes" community, and you want to find them. Unlike DNS, where there's one authoritative record for memes, to find all the different communities for memes, the local instance would have to send a search request to each other federated instance, wait for the results (what if the remote instance is offline?), figure out how to sort them, paginate them, and display them to the user.

Would it be possible? Yes, but it's probably more of a headache than the devs want to implement. If you check the issue tracker, you might find some discussion about it.

Don’t apologize! It’s a good idea and I hadn’t considered it before.

It actually does exist! But like with DNS, you have to know what you want to visit exactly. What you want is more like search engine. Try https://lemmyverse.net. Also, if you want a small instance that is federated to plenty of communities, try mine, https://lemmings.world. I use a bot to subscribe to popular communities, I'd say the content on my instance is comparable to the big ones thanks to that.