I think of top-down and bottup-up process for moderation. Top-down is when relay moderators control who is on their relay. Bottom-up is how users curate their feed. We got Mutes and WOT scores, but this is more blacklist focused.

Whitelist is the inverse - block everyone except those you want to see because you're here for a specific reason, to engage in some community about some topic. You don't care about discovery because *YOU'RE THERE FOR A SPECIFIC REASON*.

This would create lots of temporal sparsity in the network if everyone did that. Glaze your eyes at the network, fuzz it over -> Average out the time and you'll have a good approximation of any top-down created community, but completely user driven because they create the filter bubbles.