I appreciate your point of view, but mine is different. For example, at Trulia, with a dozen different apps with millions of users and rich data in the app, the

I appreciate your point of view, but mine is different. For example, at Trulia, with a dozen different apps with millions of users and rich data in the app, there is a "no nulls" policy. It's just a convention: build sparse data structures instead of passing nulls.