I is so confused

I do not understand the point of taking leftovers from the dinner table and switching them from the bowls they were served in to other bowls to put in the refrigerator. Why not just put the bowl they's in in the frig and not dirty two bowls.

Of course, it's not just two bowls, since when they get served again they will have to be put into yet another bowl. For some things, this can be an almost endless process.