Killfiles did not work well, and are part of why Usenet died. Long-time members will have good killfiles and a relatively good experience, yes, but new members start with getting every message. Building up a killfile involved a long process of deciding who was worth reading, which is a large investment when you've just started getting into a channel.

Having killfiles dictated by a central authority is completely missing the point. In the old days everyone made up their own minds.