Price it right. At the right price, it pays for everything you are talking about. At an even higher price, it is basically closing the program.

I'm not trying to suggest they _need_ to implement it. Like I said, closing it is reasonable. Completely aside from any other considerations, one could just decide that they don't feel like dealing with it. But there are other options.

The issue with "At the right price", is that your minima (what's enough to filter the spam) and maxima (what are legitimate contributors willing to put up with) can be on the wrong side of each other. The "right price", mathematically, isn't guaranteed to exist.