“serious part in either our or the USSR’s “nuclear exchange” plans.”
Not true. It is a big part of military planning. There is a big effort to harden military command and control facilities.
The area of influence of an emp is in fact as big as has been discussed in the article. But there is more to the story.
look up Mil-std-188-125-1 and check your own logic about emp not being part of military doctrine
Hardening targets you expect to get hit is one thing. But EMP wasn’t part of our attack plans, If it was really that effective we wouldn’t have needed to invent the neutron bomb.