I’m absolutely sure there are other factors. But the common denominator is Islam isn’t it?
I’m sure there was a time when Islamic theology worked for empire building. Naturally expending empires would usually absorb cultures, expend trade, increased and combine knowledge. All at the cost of the people in their way of course. It wasn’t like the Islamic golden age was great for everyone. It sucked for the people who was being conquered and didn’t want to convert.
But it’s no longer an empire, not since the fall of the Ottoman Empire. Yet they still behave like it is. I don’t see Islam separating religion and state unless you can provide evidence otherwise. And this doesn’t fit modern civilization imo.