Why? Because you think they are distracting? If your players can't keep from playing video games in your setting then mayhaps your campaign is boring, or maybe they are trying to stay entertained while waiting for the GM to finish a solo portion of the campaign. If they can't get away fromt he video games or other distractions during their turn, during the most excellent portion of the campaign then maybe they just have no will power, or would rather play by themselves in the corner then play with others.
The computer is a resource, SRDs are faster to look through then books, GMs don't have to lug fifty pounds of books to the play site, they just need their computer and a couple books that arn't on PDF (few and far between now a days).
Closing your mind to the possibilities is of what something can do for your and your Player's experience is.... narrow minded. Open your mind to the possibilities, look at new theories, and new ideas- closing your mind to the new is- well I suppose I covered that.