[lclarkmichalek]

The usual issue is the addition of control loops without much understanding of the signals (CPU utilization is a fun one), and the addition of control loops without the consideration of other control loops. For example, you might find that your cross region load balancer gets into a fight with your in-process load shedding, because the load balancer's signals do not account for load shedding (or the way they account for the load shedding is inaccurate). Other issues might be the addition of control loops to optimize service local outcomes, to the detriment of global outcomes.

My general take is that you want relatively few control loops, in positions of high leverage.