Exactly, I had at one time another write up on this subject by a professor at University of Florida, who basically stated something very similar but added more on the affects of lightning in near field POA's and how it creates a secondary current loop in near by conductors to which does not reference Earth, also to further the problem is that this secondary loop can be created between two separate cables such as two separate home runs with a cross linking audio cable or network cables, an example is when entertainment system has a sub woofer that is powered from a different circuit but has the audio feed between the surround amp on circuit A and the sub is on circuit B, I have witness this type of near field strike which vaporized this interconnecting audio cable, both the surround amp and sub woofer was plugged into a SPD strip, but because the field generated current between each home run there was no SPD's there to protect against this voltage between two separate home runs.
Another is interconnected TV's on a cable system, I have seen the tuners taken out of every TV in a house yet they all still would produce a raster and would still produce a image when alternative inputs were used, this is just some of the problem of protecting against lightning, and at the same time also shows where earth connections can fall short of there intended purpose.
