Why do people look at me in such surprise when I tell them I know Word, Excel, Powerpoint, etc?

At this temp job I was dying of boredom! All I was doing was answering the phone when it rang once every 30 minutes. I finally told the Director of Finance that if he had any work he needed done, I’d be happy to do it. I said, “I know Word, Excel, all that stuff.”
In real surprise he said, “You do?”
I said “Yes!”
So he gave me a monster spreadsheet, like, 2300 rows long, with 12 tabs, one for each month. I was to find every instance of BM, BR and IB, and then, in the far right column I was to type “Plastic.”
So, I highlighted the column where those designations were found and started searching, and pasting “Plastic.” I was just flying, barely touching the mouse, using hot keys.
Then I came to a section where it had IB repeating for about 20 rows in a row. With him watching, I pasted the word “Plastic” into the cell, then, grabbed the lower right corner of the cell, dragged it down and it posted “Plastic” in the cells I dragged through.

He nodded in satisfaction, and as he was walking away he said, “You’re smart. Like me. I like that.”

Then the HR person, who is my boss, actually, asked me to update some employee information. I entered their name, their position and their extension. Then I created a link to their email address in the cell that contained their name. She wasn’t expecting that! She told me it was a fantastic idea.

I sighed with relief. Too many people aren’t comfortable with computer related things. My old boss was one.

I have above average computer skills, better than most kids who grew up with computers I am amazed how how much basic stuff the kids don’t know. Why are people so surprised to learn this?