When Anand Kalelkar started a new job at a large insurance company, colleagues flooded him with instant messages and emails and rushed to introduce themselves in the cafeteria.

He soon learned his newfound popularity came with strings attached. Strings of code. Many of Mr. Kalelkar’s co-workers had heard he was a wizard at Microsoft Excel and were seeking his help in taming unruly spreadsheets and pivot tables gone wrong.

“People...