Can you go do that for my Facebook, Google, Adobe etc etc ad data? Their resistance to GDPR compliance is well documented.

This is the core point you’re missing. People here are talking about the industry as a whole. Not your ethical internet ad firm or you yourself.

The industry. Not you or your situation.

I’ve worked at a “marketing analytics solutions” company before (shudders at the memory).

I had access (was a data processor) to 60 million UK people’s info on their mortgage, email address, age, marital status, car make/model, likely holiday destinations... etc etc.

What we did with the data doesn’t matter. The fact it does is exist and is hidden from the customers view is the problem.