There were a large number of actual, convicted communist spies at high levels in the 1940s and 50s. Soviet penetration was massive. The Manhattan Project, State Department, Intelligence Agencies... this was around the time the US had an arms embargo against the Republic of China while the USSR supplied the Chinese Communists with weapons captured from the Japanese in Manchuria.

This revisionism that it was all just paranoid weirdo (McCarthy) harassing innocent people is a very common trope, but an a-historical one.