I was an IR major as an undergrad and I read extensively on the subject, Mr. wise guy :/

By the absence of a stable balance of powers in the Middle East, I simply mean that there is no hegemonic state in the region, and no body that can act as a substitute hegemon like NATO in Europe. This means that the different states in the Middle East are extremely insecure and face serious latent threats from all others. Consequently, holding onto power in a Middle Eastern state is often a difficult proposition.

The "almost all" caveat is based on the general pattern that I have read about consistently in the news. I don't know if the phenomenon is common enough that there is any academic/social scientific literature on the subject, although Robert Pape might have something worth looking into come to think of it. In the absence of any social scientific, quantitative data on the subject, I say "almost all" because I wanted to couch my words carefully. It is possible that some exceptions exist (although I'm not aware of any) but the impression I've gotten is that it is at least true in the vast, vast majority of cases.