Ad tech is the only reason I believe this garbage continues. Maybe we can hope and pray for some kind of regulatory relief on the horizon. Alternatively, we can start building services the way we know they need to be built, and quit our jobs when our dickhead MBA bosses order us to do inhumane things with the products.
If someone in my organization ordered me to do UA/browser filtering for our web application, I would likely quit out of protest. The primary reason no one asks for ridiculous things like this in my organization is because they are convinced that I actually will. I have made it abundantly clear to the business that certain areas of technology are no-go. Being assertive about this trash fast & early can keep it from becoming a thing in the first place. Clearly, not an option for every career & job, but developers are in such huge demand that they have a non-zero amount of control over this destiny now.