This network discovery can be really helpful. But it is one reason why you never connect to unknown WiFi. Staying in hotels, it’s always interesting to see which machines are sharing their iTunes libraries and what music folks have.
It’s a good reason to not have your name in the name of the computer/phone/device. Too easy to call out from one corner of the cafe ‘Hey, Sue’ and then when Sue looks around you have your mark.
And it’s a reason why cautious folks tend to restrict Airdrop on Apple products and not keep devices discoverable by bluetooth.
Norton’s easy guide to public wifi