Cross-instance "multireddits", that are also automatic and topic-based.

I found the issue #818 that talks about multireddits, but it seems it's about custom miltireddits that I assume would work like http://lemmy.ml/c/[email protected], which is great!

This suggestion is a continuation of that, a second step, it's about an in-built automatic multireddit http://lemmy.ml/f/design feature that would display all posts from all /c/design from all federated instances.

I believe this would help decentralization and actual usage of other instances, and also lessen the creation of echo chambers.

VERY important note: mods of all communities would need to have a checkbox to opt-in/opt-out their community's posts from being displayed on this page.