Obvious answer, but targeting is much more effective for online companies, and success is much easier to measure. An online advertising company can give much be

Obvious answer, but targeting is much more effective for online companies, and success is much easier to measure. An online advertising company can give much better, more quantifiable ROI by targeting specific users more likely to convert: in Google's case, it's largely due to the desire to click inherent in search, whereas in Facebook's case it's through deep demographic information. They can also directly measure the effect an advertisement has, by measuring click throughs, etc. Compared to the much more nebulous effects of TV/print ads, this can be highly appealing.