I don’t have a dork disk (spoke protector), so I might be wrong, but the issue I see with the current ones is that the are attached to the component they are trying to protect; the spokes.

I think the old steel ones went on the threaded section of the hub and were held on by the freewheel. The newer ones are plastic and clip onto the spokes.

So instead of shielding the spokes from the impact of a chain falling in between the lowest cog and the spokes, the spokes have to absorb the impact. I would think the current ones provide some amount of protection in keeping the derailleur/chain from getting entangled with a wheel, unless the disk breaks, but being able to attach to the hub/cassette would probably be better.

John