Hide ye not your new wine under a bushel

To completely mix up two biblical metaphors, why do more pubs not take advantage of modern technology to tell people what new beers they have available?

Some get it. Homebrewjapan got an email from his local specialist beer bar when they got Ruination in. The Gunmakers tweet when they put a fresh cask on.

Costs approximately the same in effort as putting the pump clip on, and attracts hordes of beer tickers to your bar.

OK, I suppose I understand now.