Why do we own so many beds?

I took this pic last night when I went to turn out all the lights in the house.

I keep finding all three younger kids piled together asleep in one twin bed. For some reason, it reminds me of a book I read them called "Going to Sleep on the Farm". On the pig page it says, "A pig curls up with its family and friends. Where one pig starts another pig ends." So, its not a pig pile. Its a kid pile. :)