I'm not saying those spaces can't be used. Ideally each instance would end up with its own set of popular communities that have become the one true community. But it's a much better user experience if every instance doesn't have all of the communities from every other instance duplicated.
Okay, but I see no reason to intentionally make that issue worse.
Because if I subscribe to all of them, sometimes I will see 100 identical posts of the relevant news. And if I subscribe to just one, then I'm missing out on a lot of content.
At first I thought this was a good idea, but now I'm not sure. Instead of encouraging the need for that sort of manual work to group every similar community for every topic, I think we should let the communities naturally converge on the winning community.