6. Waterfall ought to work, but agile actually does
Long before formal development methodologies drained the fun out of IT, business managers used to wander over and ask, “Can you get the computer to do this?” The programmer would try something, show it to the business user, and they’d iterate until it was right.
They didn’t call it agile. They called it “having a conversation about what the computer should do,” but it was agile, nonetheless.
Then waterfall methodologies came along. They’d work, too ... if business managers could perfectly envision a complete working system and describe it precisely. But they can’t, so we lost 30 years of productivity.
Enter Scrum, which takes iteration and interaction, and adds enough methodology to drain most of the fun from IT that other versions of agile had put back in.