Pondering this some more ... there are two different "audiences" here: party organizers and attendees. A Calendar benefits the former to the extent it can discourage "competing" events. As an attendee, I'm not so much interested in trying to fill an otherwise vacant weekend, as knowing when we will see the next Catman Do.

Needless to say, most of us are far more likely to be attendees than organizers. And I'm not convinced it's necessary or even desirable to "protect" events from each other.