This is an interesting question don't you think? Why shouldn't there be some sort of penalty for bogus copyright claims?
Just to give an idea of the scope of the issue, Google previously noted that 37% of all DMCA notices they receive are not valid copyright claims. One of the problems is that many rightsholders use completely automated systems to inform Google and other sites of infringements. They swear under penalty of perjury that their notices are correct, but this is often an outright lie.