Those PDAs generally used styluses, similarly sized screens (or at least about half the size of current phones, 4-5", so a very different DPI) and it was consid

Those PDAs generally used styluses, similarly sized screens (or at least about half the size of current phones, 4-5", so a very different DPI) and it was considered okay to make interface elements so small that you could not walk and reliably hit them at the same time. By your logic we should be able to use a PDA interface on a smartwatch.