maybe for extremely noisy supplies like usb power, dirty switchers, or driven devices like servo, relay, or motor. in these cases an inductance or small series resistance is also recommended. admittedly ive seen it help low current circuits in situations involving flaky battery holders too. in the uno i suspect its more to stop the ldo from singing because according to spec the .1 alone is not up to that task.
however for me .1 does the job in most battery applications and that is the standard advice for hobbyists. of course we are all entitled to our own theories and guidelines and its unlikely to do any harm. except possibly a slight reduction in reliability due to the extra component itself.