In the Beginning... ...there was no inheritance and no composition, only code. And the code was unwieldy, repetitive, blocky, unhappy, verbose, and tired. Copy and Paste were the primary mechanisms of code reuse. Procedures and functions were rare, newfangled gadgets viewed with suspicion. Calling a procedure was expensive! Separating pieces of code from the main logic caused confusion! It was a Dark Time.
One of the key objectives of a project inception is to collect requirements collaboratively. But, many times, it is difficult to decide where to start and what to focus on. Story mapping is an engaging activity where all participants are involved in the process of building the product backlog on a wall, versus writing a dull 100-page requirement document.