There are so many challenges with building a social app, especially around contacts... I'm not sure how they'll mitigate all this stuff, but fun to think about it and hope they do succeed in doing so anyway.<p>A few considerations off the top of my head:<p>- relationships are extremely fragile and can exist in all sorts of awkward middle states, outside of just "friend enough to notify when I'm in town" vs not. the risk of creating awkward meatspace side effects is extremely high with this kind of thing, with very large downside risk that human beings are very attuned to. for example: exes, former bosses or colleagues gone sideways, people you said something weird to once at a party, stalkers, etc. are all people you might have in your contacts<p>- relatedly, contacts growing out of sync organically over time is actually a feature, not a bug. it's easy to let contacts die when they die by themselves without having to prune them -- and nobody's delicate feelings get hurt by letting this happen<p>- existing on a mobile phone while not being an attention-sucking nightmare cesspool -- while also not /creating/ another attention-sucking cesspool, despite having all the social data necessary to do so -- seems like an impossible challenge. how do you get people to remember your little app in a sea of Trending Flamebait notifications? (others have noted this related to funding model, but that part feels surmountable, especially as a passion project from a billionaire)