This doesn't really work because it doesn't allow a moderator to set the tenor of a community. People can filter out individual messages, but a dedicated set of bad actors can turn a community into swiss cheese or undermine discussion just by spamming, baiting and trolling and taking advantage of the variance in the level of tolerance for the bad behavior.

Communities function when there is a standard to which the community members adhere and when bad behavior is uniformly moderated away. Making each individual have their own moderation bubble is a recipe for incoherence, even with the improvements you suggest. Its also a lot of work.