If you want any convincing, next time you fly an ILS in VMC try flying to full scale below the glideslope (whilst still keeping the needle alive) and then have a look when you get to 1/2 mile from touchdown at how close the ground is!
And anyway, if you can fly it and keep it at less than full scale deflection (otherwise you 'peg the needles'), why can't you fly it to within half scale? It's the same process, only within narrower margins.
Do you attach the same "almost there" criteria to the rest of your flying (approach speeds, W&B, level keeping etc)??
Edited because the ground will always be the same distance away at DH! You'll just reach DH earlier than normal if you're below the GS.