I don't think that you can compare a broken business model with abuse of a system by spammers and others hell bent on destroying some of the nicer sites that well meaning teams have developed.

By that analogy usenet was 'asking for it' because it was open, worked and actually contained great content. Of course that meant that it was ideal for the jerks of this world to try to peddle their wares, eventually resulting in the near destruction of usenet.

On the web the relationship between the number of people that you have to employ to look after abusers vs the number of people that are actually productive is a good way to measure your success....