[bee_rider]

This seems like so obvious an observation that I don’t get why advertisers haven’t made it. If I’m in work-mode, and you show me an ad related to a hobby of mine, I have a 0% chance of clicking it. If you show me an ad related to my work, it is probably more like .01%. Which is still an infinite-times improvement.

[klyrs]

It's because there's an arms race to maximally exploit the massive amount of data they're collecting about individuals. The more specificity you can claim, the more the ad-buyers will pay. I'm not convinced it's doing any good, but I think a draw-down would be a hard sell for all parties involved in that market.