A growing organization can bring pain on many fronts. One of them being well-defined product development documents and timelines. You accept that even the 10X engineer in your team will miss things.
A well-defined process helps and takes lots of pain away from the testing team, support engineers, and customers.
The best of the best developers are known for losing focus too quickly. Not having a well-defined scope, timelines, and managerial supervision will result in a science project not shipping a saleable product.
The airline industry has a practice of SOP for the same reason. A pilot with thousands of miles flying hours is mandated to follow the same as a newbie joining a job fresh from an institute.