That is the only way to battle spam with 100% effectiveness, yes. But there are other ways to do it that can still be very good, even though they're not perfect

That is the only way to battle spam with 100% effectiveness, yes. But there are other ways to do it that can still be very good, even though they're not perfect. The filtering for comment spam in Ping is subpar, and I don't think the difficulty of the task excuses the fact that Apple has done a poor job.