In a purely distilled water enviroment with NO outside Nutrients added, you will get a seedling to pop and it will expend what energy was stored in seed form... once that energy is expended, the seedling will slowly starve to death caniballizing itself. If you are cloning in water only, the same thing will happen, the cutting will use stored energy to produce roots, however is there are no nutrients in the water. The new young plant will start to eat itself into a slow death hoping that a suppliy of nutrients will become available before death..... That is kinda natures way of trying to survive...... There is no nutes in distilled water. only H2O.... and the oxygen in the water does not come from the water in a DWC enviroment, it comes from the agitation of the water with the bubbles... More air comes in contact with the water molecules and that equates to more dissolved O2 in the water......
If water sits still and the surface is not disturbed and there is usage of the O2 in the water.... the Dissolved O2 in the water will drop to a point where large scale death will occur in the body of water... That is what happens when a pond 'turns over' and all the fish die.