I'm as scared as the next person of all the data being sucked up but if I wanted to be charitable, ... a different pov is perfect advertising which would effectively read your mind and present you info exactly when you need it. Thinking about going on vacation to Vietnam? perfect advertizing would devine that and show you ads for good hotel deals, flights, attractions, restaurants, events, markets, etc in Vietnam. Perfect advertising would also not present ads for things you'd already done there unless it knew you'd probably want to do them again. It would know if you're an adventurous eater or a conservative eater and present you with restaurants that meet your preferences. If you're a thrillseeker it would present you with thrilling activity options. If you're a clubber you'd get ads for the best clubs featuring the artists that fit your preferences best.

Perfect advertising could read your mood tonight and suggest restaurants if your mood indicated you wanted to go out. I could know which ones are already booked solid and not present them. It would would know if wanted a quiet intimate dinner or a louder venue. It would know which friends are free and suggest asking them along.

Yes I'm scared of some of the repercussion of getting to that state and all the abuse and how it will probably never get there but it's certainly a fun thought experiment to imagine what perfect advertising might be.