How Many Plot Types Are There?

We like to think that our stories are unique, that we thought them up all by ourselves, that we're the only ones who can write this story this way. (I believe this too.)

Then someone decides to count up the number of basic plots, and it's always a small number. I've heard there are 32 "masterplots" out there, and 12.... 

Here's an essay that claims there are only SIX basic plots. What do you think? Is this too reductive? Is it beside the point, because stories are different, even if "plots" are similar? (That is, a "fish out of water" plot is a different story when it's about a child, say, rather than an adult- what happens isn't as important as who it happens to.)