I see a lot of things around this city that I'm curious about, but haven't the faintest clue about how to start researching them. And even if I can find an article or two online, there is a massive amount of valuable contextual information that's usually missing, unless I scour the web for obscure blogs. For instance, what are those little people statues at the 14th St. 8th Ave. subway station? A google search doesn't return anything immediately enough for me. And many of these questions are spur of the moment. So posting a picture with a question is significantly better in capturing in-the-moment curiosities.
But why can't you post to Facebook or Twitter?! Because I have tons of questions that I'd rather not bombard my friends with. And because the chances of getting just a reply go up the larger the network. If I can tap into the minds of my friends' friends, why not? FB and Twitter are not platforms for asking questions. There's a reason why you never get Quora-like answers. Or why you aren't connected to people who're likely to have the answers you're looking for. There are fundamentally different use cases between FB and Twitter and Quora, and perhaps now Jelly.
So please stop acting thick and think for a second why this might be a little different. Yes, you can ask friends for answers. Yes you can search Wikipedia. But do they have all the answers? Are there types of questions they're just not suited to handle? Can the answers be more rich? Can getting those answers be easier and more enjoyable? Maybe.