There's going to be a lot of people who don't have a laptop/desktop handy right now - because they're out of the house, because it's unplugged in a cupboard, or because they borrow it from a friend or use an internet cafe when they need that. So a requirement to use that and connect your phone to it is effectively similar to the 24 hr waiting period: time to think, time to mention it to a friend who's heard about this scam before. This is why phones are such an attractive target in the first place.