for me, some ads also utterly ruin the brand of the ad host.
For example: here in France we have this one company whose business model is "get a 18.xx€ refund on your order (20€/mo subscription)". its rather obvious how this kind of system makes money.
i had some elderly family members get scammed this way, and I absolutely refuse to ever return to any webside that displays this "offer from our partner". after checkout ofc.
so i get my train tickets on trainline, and amazon gets what businesses fnac and darty should have gotten. manomano must've lost a couple thousand euros of purchases from me already, hope it was worth it to them.