"Yes, I see now."

You did see from the beginning ;-) array of array refs is the same as two dimentional array. Put in this way, two dimentional array is the logical view across languages, and array of array refs is the Perl way of realize the concept.

Due to the fact that the second level arrays are not required to have the same length in Perl, they have to be refs, so that the information about their lengthes is not lost because of the flattening.