@Ricky Absolutely - Perlman argues that duplicate addressing is redundant and you only require addresses at layer 3. I can absolutely follow that argument but then again, we couldn't do all the things we do today by treating IP as an overlay network where we control the local flow by MAC addressing. Of course, there would be other ways to do the same, but given the more or less negligible overhead for 'redundant' addressing, there are significant benefits.