That's a solution to mitigate losses but it doesn't address the fact that someone has lost money due to fraud - and I'm guessing it hurts small businesses the most.

Strategy-wise the solution is simple, but digital marketing is intrinsically flawed nowadays and it's one industry that could literally be turned upside down at some point in the coming decades as the internet evolves. And I think a lot of people wouldn't mind that - especially the people with the power to bring the change (i.e. developers and proponents of open source solutions and haters of crappy spam)

> it doesn't address the fact that someone has lost money due to fraud

You would try it out with a few hundreds or possibly thousands first. If it isn't showing any return at all, something is fishy. You wouldn't with a sum that would hurt to lose.

Then nice thing about the web is that we can measure and analyze user behavior.

Of course. I'm not saying it isn't possible to have a profitable marketing campaign despite fraudor limit your losses (just starts to cost more since some industries are more impacted than others). I'm just pointing out that it's inherently a fraudulent/sketchy industry and therefore very subject to potential disruption.