Perhaps it would be useful to look at the subscriber numbers for these communities? Maybe contact some of those subscribers directly, since they are the ones who requested the content in the first place? I would venture that people interested in a non-interactive firehose of links is probably a lurker and wouldn’t respond here.

If a lot of these communities have one subscriber, It could be that someone subscribed just to get the community on All.

I’m generally of the view that defederation to curate content is a bad idea. I’ve seen suggestions to have the ability for an instance to exclude certain communities from All, or maybe Lemmy needs a semi curated Popular feed like Reddit.