Bit rude, yeah, but sometimes it’s better to be rude than let someone cross your boundaries. How much more awkward is it if you say “yes” or “maybe” and then they ask if they can borrow your phone or something and you have to evaluate whether you trust this random person while they’re looking right at you? A lot of people are definitely asking this way because it gets you to let your guard down and they know you would’ve said no if they’d just straight asked. Personally I tend to respond with “you can ask” or something like that. Making it pretty clear that I’m skeptical of what they’re going to ask. But my default assumption of other people in a city is that they’re potentially either trying to scam me or rob me.