We're in agreement. It's a filter, not a metric: you can say this product worked, as in it did what it said on the tin, but the worse/better comparison doesn't

We're in agreement. It's a filter, not a metric: you can say this product worked, as in it did what it said on the tin, but the worse/better comparison doesn't work out. The other aspect of "at some point you can just build it and it works or doesn't" is that when it's built, you can (ideally) just go read the code and find out how it works. It's ye olde issue of "it would take me almost as long to explain it as to make it..." - if I'm having trouble communicating an idea, I can just go make it, and then show it to you.