It's a cult as much using source control system, build system, and editor (IDE) is. e.g. you can always code, and zip-up files, and build directly using comman

It's a cult as much using source control system, build system, and editor (IDE) is. e.g. you can always code, and zip-up files, and build directly using command-line (we still can do it, right?), but when you need to deliver that automation bit, and most importantly hand-off to the next person what you've done - e.g. codified for real, then it becomes a must to have a system like this.