Is there any noticeable difference between mochi made from pounded rice, versus mochi made from mixing rice flour and water together and cooking briefly? If not, why bother with the labor-intensive pounding method? 
I think it's because there is water inside the gnocchi paste, which turns into vapor and builds up pressure. A little bit like why you shouldn't throw an ice cube in hot oil.  You can pan fry them, but not deep-fry them. 