I suspect most useful communities will be full of spam post requests very quickly. Like 10x more spam posts than actual content. So, removing things from the community (by adding a flagged event is not good - too many flags to download just to filter bad stuff out). There is no filter in Nostr relays for posts that have NOT been reported. The client must download everything.
That's why I only created the pre-moseration. It makes the job of listening clients easier while allowing post approval apps to offer automatically "approve everything from trusted authors"-type of feature.