I agree with what you said about developers understanding what does on under the curtains, but regarding the NewRelic statement, I couldn't disagree more with this.

Spending time early on in the project on things that don't matter and that don't really impact the system, like the example given in the post, is exactly the kind of thing that ends up creating projects that are expensive to maintain and just bad.

Focusing on solving large performance bottlenecks, that can easily improve things 1000 times more than fixing that simple example is a much better use of your time, and is what newRelic shows you.