Yeah...a 16 horsepower Yanmar in a 4 Ton boat idling in reverse could rip the cleats right out of the dock!
I DO approach as slowly as possible (I am the OP to this thread titled "Slow down when docking" BTW!).
If you really read the post you quoted, you would see the boat is still moving forward when I step off. The reverse prop provides a little braking action, then eventually, some resistance to the bow line, keeping the boat against the dock (and not my neighbor) until I get the other lines on.
You will be shocked to know that when I single hand, I put the boat in reverse, and walk it out of the slip, holding the shrouds, and stepping aboard as I approach the end of the dock.
Could I trip on the dock and be knocked unconscious, allowing the boat to slowly idle across the Fairway coming to rest against whatever it contacts? Sure. However, it is highly unlikely. That's the worst case scenario, and given all the things that COULD happen to me while sailing, is the least of my worries!