Without a process, some of the knowledge of “what we do here” and as importantly, “how we do things round here” and “why we do what we do” gets lost every time one of your ‘good people’ leaves. This knowledge also gets changed as new people join.
This can be overcome by a founder that spends time and energy ‘policing’ the culture (think Steve Jobs), but one day even the founder will disappear.
Process gives your business a memory of its own.
That memory needn’t be prescriptive. The most detailed score still leaves room for interpretation, and you can make it more improv if that’s your style.
If the business always remembers the “what”, “how” and “why”, your people don’t need to make it up as they go along.