Back then it was the most normal thing in the world, and obviously true to any but the most unnaturally twisted minds that the proper role of a man was to earn a salary sufficient to support the whole family, and the proper role of a woman to be a housewife and mother.

Thus, a woman who worked while married was shirking her duties to her husband and children, and taking away some man's chance to build a family. And that man was probably a war veteran! Support the troops!!!

IBM's shareholder would probably have sold their shared in disgust and boycotted their products if they had openly undermined these norms.