Don't play portable games in Japanese Arcades kid!

First thought that came to mind was, why would you be playing portable games in an arcade?
Second thought, why would you even care? if they are there they will probably pay to play a few arcade games!

Ok so this sign has been translated as "social networking titles and portable games are not permitted. Those who are discovered playing either of these will have to leave! Puzzle & Dragons Is Prohibited, those with manners don't bring food they've purchased elsewhere into restaurants"

first thing to get out of the road, Puzzle & Dragon's is a puzzle game featuring dragons for the iPhone and Android, what else do you need to know?

So here we go, why doe's it matter if you play a portable game in an arcade, if you're there you are probably going to pay for a game, perhaps you're waiting in a line or waiting for your turn so you turned on your device to play that till you play your game, personally I think this rule is silly, and the next bit, about food, if you buy food from a restaurant why would you go to another?
it's not the same, if you buy food, and eat it in a different restaurant  you're not likely to buy something from that restaurant  but if you go into an arcade with or without a portable device you will probably play a game there!

Anyways what are your thoughts on this issue of playing portable games in arcades?
please comment bellow!