Im genuinely curious, with all these bashing going around. How is it the fault of ads vendors when website/webapp publishers are the ones that put ads on them?

Im genuinely curious, with all these bashing going around. How is it the fault of ads vendors when website/webapp publishers are the ones that put ads on them? Like one day Wikipedia inserts ads on their pages to keep the lights on. We bash Google for blocking uBlock? I feel like I'm missing out on something. Please help me understand.