Ask a leftist. He’ll give you the answer. It was those Hollywood people,Trumbo, Lawson, Hellman, Chandler, etc. You know, “The House un-American Activities Committee”. But McCarthy was a “SENATOR”, having nothing to do with “The House Committee on Un-American Activities”. Note the difference in a “liberals” name for the committee. Grammatically it has the Committee “committing” the un-American activities. You can tell a leftist by the way they say the name
I always enjoy watching committed leftists stepping on their own crank by committing that error.
Unfortunately, they have no shame. It usually has no effect.