I worked at a similarly sized company to Dropbox, and when I questioned product decisions I would often receive similarly smug put downs. How could you possibly think you know more than the CEO?
And then I watched over the next few years as the product strategy floundered, reorging many times without shipping anything concrete.
I suppose what I’m saying is that while your comment shuts down conversation quite effectively, it can still be wrong. Sometimes - quite frequently, in fact! - there is no man behind the curtain. Sometimes, when product decisions seem questionable, they really are questionable.
(Sorry if I have an annoyed tone; I think I'm subconsciously venting against all the times I've heard this from others in the past.)