BBQ would not be allowed in my third floor apartment's balcony as it would stink up the place and it would be dangerous as well and I have no idea where could I store the equipment when not used as we have not much unused space, and my neighbors would be very creeped out if I would just ring on their door and invite them. We live in the same apartment since 2012 and never even talked to neighbors or had a chat. People tend to be very indifferent with each other in this apartment complex and I have no better experience with former ones either. These guys are trying to make a site that acts as an icebreaker - if you really need dog-sitting one day you can try to ask there and if someone helps you out then you have a form of connection and maybe will have a chat after it or something and maybe greet each other and stop for a chat the next time you see each other. The very idea is that the world is urbanizing, due to jobs and all that people who like the more communal village lifestyle are forced into cities where they suffer from the general indifference and impersonality so they try to change it and make cities more village like or suburbia like. They try to counter-act the negative psychological effects of urbanization with a "let's open our doors to each other" theme.

As for selling data, they have the same data as my utility company. They can link a name with an address. Anyone who walks up to our house will see the name on the door anyway. And a photo, so OK that is more. But overally this is not secret data nor very sensitive.