Earlier quoted context omitted.
Give the Sequoia guys the benefit of doubt. They probably have seen something more (related to the product) that the rest of us havent or might be privy to other features in the pipeline. Obviously, they're a bunch of smart people who have backed some of the biggest companies in the tech landscape. In short, dont be so hasty to judge.
I've been hearing that about Twitter for years now, and I'm still waiting.
Twitter might still not have a viable business model, but they can experiment (now that they have a huge user base and data) and try to find one. While its not easy and obvious at times to find a viable business model, just reaching the sheer distribution scale as Twitter's is a huge hurdle in itself that very few incumbents will ever reach.