Earlier quoted context omitted.
If you're an advertising platform, you can choose what sort of products are advertised on it. All of them do. You can, quite reasonably, decline to advertise things that are unethical. For instance, predatory loans. You are choosing not to profit off the misery of others. This is not nearly as complicated as you make it out to be.
Will the target demographics universally and unequivocally benefit when online access to such loans is cut off? Other choices might include an even more predatory local check-cashing place and a guy named Vinnie who seems to own a lot of baseball bats for someone that never plays baseball.
This doesn't 'cut off access'. Last year Google stopped advertising predatory lenders entirely. Targeting ads for predatory lenders at potentially vulnerable people is even worse. Again, this is a pretty straightforward thing, not a complex logic puzzle that requires careful derivation from fundamental axioms.