Take the Iraq example, isn’t it likely that if a Kurdish enclave would have been created by the British, that the Kurds would have suffered much less and perhaps even had succeeded in building a well functioning state? For the Kurds it is quite clear that the issue of borders was and is THE problem.
“To me, the necessary ingredient for success is a viable political system and economic development; issues of borders and minorities and ethnic homogeneity are secondary.”
I believe that both ingredients are necessary.What you don’t want to acknowledge is that political and economical development are so much easier with natural borders and homogeneity. In fact, one leads to the other. We don’t have much data to work with but clearly, the more homogeneous a state is in our region the more it is likely to succeed or the more it is likely to avoid civil strife. Arab societies faced huge challenges anyway modernizing. Add to that the artificial borders and you were stacking the odds against them.
To become a great basketball center you need to be tall but you also need to practice a lot. Both are necessary conditions. Yes, you can argue that you just need to practice and that there were a few smaller centers that made it into the NBA. But you should agree, that your chances of making it, no matter how much you practice are much, much smaller. The Sykes-Picot borders made the Arab states “short” as per this analogy. It made developing an open and trust based society very, very difficult. You are telling them they just didn’t “practice” enough.