How complex can it be, running a datacenter?
A datacenter has quite a number of variables that are all interlinked. Think of the air temperature at server level, the temperature at the inlet and outlet of the CRAC, the airspeed, the efficiency level of the various infrastructural devices. Then there are the time dependable energy demands of servers. Some cluster peak during the night, others are more active during office hours.
While you are juggling with all these parameters you need to consider the redundancy of all your machinery at the same time so that no single failure leads to an outage. If you are still able to keep all these balls in the air you also have to mind servicing all that hardware and keep your redundancy up during that maintenance moment, oh and do all this while using the minimum amount of energy possible.
Get it? It is almost an impossible task for humans to manage. Machines are capable of doing the math almost infinite times fasters than humans.