I was trying to say that someone could simply use "why not just use FB?" as a way to dismiss any new service built on a social network. I could've easily said that when Quora first launched. But now we see that Quora fills a particular niche that FB doesn't seem to excel at. Similarly, we may see Jelly carve out a corner for itself (whether it's for "spur of the moment answers service" or otherwise), a corner that FB may have overlooked or is just not currently built to handle properly.