The instability we see is definitely not a function of design. If you have studied any of it you will quickly realise that this is situation that has many actors that act based on their own interest and absolutely nobody has control over it. Those that attempt to control it usually end up creating a hole host of unintended consequences even if they sometimes manage to achieve their main goal.
Its however true, that in some limited cases, creating more chaos can potentially help you. Such cases definitely exist but they are not the majority of strategies used. Syria releasing of Jihadist to split the rebels is a interesting example of such a strategy. It usually is a strategy of the weak, not the strong. The strong prefer control, not chaos.
The idea that it would be best to throw everything in chaos is completely wrong and even the leaders of the super powers understand that. Only if you assume that their is some sinister conspiracy that has completely different values thats operating under our institutions, could such a policy be explained. I see 0 evidence for such a conspiracy.