With the caveat that deer will eat anything if hungry enough, has it been your experience that deer like Deutzia?
Have not seen any damage, but due to variations in behavior between sites and times you really need to fence them out to have any control over the situation. Otherwise the animals are deciding for you how you are going to be able to garden. Wire mesh stapled to peeler poles is not that expensive or intrusive. Finding a long-established shrub in your garden suddenly nibbled to nubs can, on the other hand make you feel quite intruded upon.