One benefit of tied objects is that, depending on how the class they're tied to behaves, one can slip them in in place of a scalar type, without most of the code knowing the difference. Aside from the well-known example of tying a hash to a DBM file -- transparently moving a hash from in-memory to on-disk, tying can be incredibly handy for some profiling and debugging work, as when you find yourself in the position of needing to count how many times a value gets read or written.