Yes, they would be a serious ground sink-but lightning is so much more powerful than anything we normally work with I wonder if it would be enough-or just spread the gradient over a larger area? Around here I get nervous because fences run for miles tied to t-posts. That should ground the fence-but that feeder the cows were around was very well grounded as well.
The feeder may have been well-grounded, but the ground distribution was still over a concentrated area -- really, no different from a point ground such as a tree.
The common grounding through the grounded neutral conductor of the utility distribution system probably would provide some shunting of current from a direct lightning strike. However, the majority of the current likely would be to the nearest grounding electrode as that would be the path of least resistance. If the air around the conductor to that electrode becomes ionized, that also will be a current path. So you could still have a significant voltage gradient around the electrode, but it may not cover as large of an area. I wouldn't want to be standing anywhere near a power pole in a lightning storm.