At its core systems thinking is an antidote to reductionism. The essential feature of a system is that it is an indivisible whole and that its features are more than the sum of its parts. Systems lose their properties when taken apart into components, because their properties are the result of interactions between components, not the sum of the properties of components in isolation.
That insight produces the most important practical application of systems thinking, which is that systems always need to be designed from the ground up. People should never try to improve individual metrics, but only improve parts if it improves the whole. That's also what most of the examples in Maedow's book are about that's quoted in the piece.
It's also quite funny to bring up a transition to microservices in the piece in this context. I think microservice architectures are almost always the result of ignoring systems thinking lessons. People start to think in terms of the performance of each individual service, start to develop each service on its own terms, and start to ignore the fact that what matters is the interaction between services. It's exactly the kind of silo-ing that systems approaches try to avoid.