Photoperiod plants can be cloned because they can be kept in veg for however long you want and can theoreticly live forever, so its possible to grow a whole new plant from a cutting. AUtoflowers however start flowering automaticly when they reach maturity and die at the end of their flowering cycle, since any cuttings you take from an auto will be the same age as the mother plant they will start flowering at the same time making it imposibble to veg them into a new plant, nearly imposible to get them to root and in general its just a waste of time as they will finish flowering and die at roughly the same time the mother does