Modern software engineer is in most cases just a bricklayer - he just realises a vision of the business (product owner and his boss etc.). So, in your example,

Modern software engineer is in most cases just a bricklayer - he just realises a vision of the business (product owner and his boss etc.). So, in your example, it's not the software engineer who increased retention rates, but rather the manager who thought of writing such improvement, and hired an engineer who then implemented it. In other words, the implementation is seen as a trivial part of the process, while figuring out what exactly to implement is seen as the core of the value creation.