So, for the situation highlighted above in magenta, I just do not see this as a real situation.
.
In this case we were being driven backwards into the end of the bay and the railroad trestle crossing it by strong winds and waves that had not been forecast to arrrive for another six hours at which point we would have been long gone.
When my wife woke up and realized what was happening, we started the engines but we could not power forward because we'd have run over our own rode and put it into one prop or the other or snagged the rudders.
The original windlass to the boat was very slow. So my wife would power us forward until I signaled her to stop before we ran over the rode. Of course as soon as she stopped the boat instantly began to be blown and knocked backwards by the wind and waves. As the windlass pulled more rode in I'd signal her to come forward again. We were in about 10 feet of water at this point (we'd anchored in 40) and the trestle was less than a boat length behind us.
It was a case of taking one step forward and two steps back.
When it was obvious we were going to lose the race I had actually started reaching for the windlass clutch wheel to let the chain run back out and cut the line on the bitter end when the anchor came out of the water. I signaled my wife to go forward and she did. The trestle at that point was perhaps half a boat length behind us.
We also have friends who one night drug the better part of a mile from where they had been anchored over to the base of the cliffs on the island across the channel from them. They woke up just before colliding with the cliffs and started the engine and got out. In this case, they were in pretty deep water at the base of the cliffs and I don't even know if their anchor was on the bottom at that point.
Our slip neighbors told us they were in the southwestern Pacific in their 40' sloop anchored in an exposed anchorage with other boats when the winds and waves came up unexpectedly. There was a reef about three boat lengths behind them. Boats around them were dragging--- one went onto the reef before they could get their engine going and anchor up. Our slip neighbor's anchor held (Rocna) and they had no problems. But they were prepared to take action should it have become necessary, including cutting the anchor and rode free and powering away.
These kinds of incidents are rare, I'm sure, but they can and do happen. In our case, it inspired us to go in search of a better anchor. But we still have a length of line on the end of our chain rode that will appear on deck (having it go over the wildcat will do no damage to anything) where it can be cut with a line knife which we now keep handy just inside the main cabin door.