Excellent point. In fact, some conspiracy-minded historians have suggested that the whole Wallis Simpson business was just a convenient pretext to force his abdication, the real reason being his unsavoury political views. You're right about it being unfair for Elizabeth to blame Wallis for her husband's early death, but that is apparently how she feels, and it's something Margaret would have had to take into account when deciding whether or not to follow the same path as her uncle.