Wow!
When I read about a C 150 having done this with a 50 pound concrete block, I though it was an urban legend. I suppose it could have happened.
For reference, the much older Cessna Pilot's Handbooks specify 700 pounds as the appropriate capacity for a tiedown. I once landed in Manitoba, right after a windstorm had gone through. I saw a dozen or so aircraft on their backs with concrete blocks, and screw in anchors still attached to the aircraft by the ropes, but otherwise utterly useless.