During his commencement address at the University of Southern California last week, Microsoft (Nasdaq: MSFT) CEO Steve Ballmer recounted the time he told his parents about his decision to join the infant software company.

"My father comes up out of his chair. 'What's software?' Pretty inconceivable today. My mother asked an even more interesting question for the year 1980: 'Why would a person ever need a computer?'"

Just goes to show that in the world of technology, what seems like common sense today was wacky and innovative yesterday.

Fast-forward a quarter-century. Steven Levy's excellent book In The Plex: How Google Thinks, Works, and Shapes Our Lives gives a refreshingly ironic example of Microsoft's other top dog, Bill Gates, showing the same bewilderment toward Google's (Nasdaq: GOOG) Gmail as Ballmer's parents showed toward software:

"Have you played with Gmail?' I asked [Gates in 2004].

"Oh sure, I play with everything," he replied. "I play with A-Mail, B-Mail, C-Mail, I play with all of them."

My editor and I explained that the IT department at Newsweek gave us barely enough storage to hold a few days' mail, and we both forwarded everything to Gmail so we wouldn't have to spend our time deciding what to delete. Only a few months after starting this, both of us had consumed more than half of Gmail's 2-gigabyte free storage space.

Gates looked stunned, as if I offended him. "How could you need more than a gig?" he asked. "What've you got in there? Movies? PowerPoint presentations?"

No, just lots of mail.

He began firing questions. "How many messages are there?" he demanded. "Seriously, I'm trying to understand whether it's the number of messages or the size of messages." After doing the math in his head, he came to the conclusion that Google was doing something wrong ...

Gates' implicit criticism of Gmail was that it was wasteful in its means of storing each email. ... Despite his currency with cutting-edge technologies, his mentality was anchored in the old paradigm of storage being a commodity that must be conserved.

Pretty inconceivable today, you might say.

Seven years and about 200 million happy Gmailers later, it's safe to say Google wasn't doing anything wrong by offering users a then-unheard-of 2 gigs of storage. It was doing just what Microsoft did a generation before: anticipating what consumers want and delivering it on a massive scale.

Fool contributor Morgan Housel owns shares of Microsoft. And a Gmail account. You can follow him on Twitter @TMFHousel. The Motley Fool owns shares of Microsoft and Google. Motley Fool newsletter services have recommended buying shares of Microsoft and Google, as well as creating a diagonal call position in Microsoft. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.