Yea they were absolutely exhausted in terms of economics and demographics but it is so much more than that too which the article touches on.
The lands in the middle east changed hands so many times that you had a generation be born and grow into adulthood without having being firmly associated with one empire or the other.
You had the nomadic tribes grow rich from their mercenary work for either empire.
You also had the fact that both Christian and Zoroastrian faiths took huge blows as the true cross was stolen by the Persians and then the Roman army destroyed the most important Zoroastrian fire temple and snuffed out the eternal flame there.
And finally after the Persians were defeated by the Caliphate, you the the Romans, against their well established strategies, gather their forces for a decisive battle, and then make tactical mistakes allowing for defeat.
It was the perfect storm of the right place, at the right time, with rolling nat 20s.
I don't buy the 'huge blows as the true cross was stolen' story. Christianity did fine for 100s of years in the region. Conversion happened very slowly over a long period of time.
Its not even clear how 'Islamic' the early armies were, they might have considerable Christian and Jewish portions. How differentiated early Islam was from certain version if Christianity is up for debated.
I also think just going with the 'right place, right time' narrative misses good coalition billing, good generalship and other things they did very well. Both Rome and Persia had thought a great number of wars in its history, and faced many 'barbarian' invasion, sometimes from forces that on paper were more impressive, that invaded during ongoing peer conflicts and despite that had been successful.
There does seem to be a tipping point where a place tips from a fairly organized society and constant warfare / conflict just becomes the norm and social and economic forces evolve to supply it ... and effectively keep it going even if it is not in society's best interest. Not a lot of peaceful alternatives at that point that aren't highly vulnerable to the cycle of conflict.
The lands in the middle east changed hands so many times that you had a generation be born and grow into adulthood without having being firmly associated with one empire or the other.
You had the nomadic tribes grow rich from their mercenary work for either empire.
You also had the fact that both Christian and Zoroastrian faiths took huge blows as the true cross was stolen by the Persians and then the Roman army destroyed the most important Zoroastrian fire temple and snuffed out the eternal flame there.
And finally after the Persians were defeated by the Caliphate, you the the Romans, against their well established strategies, gather their forces for a decisive battle, and then make tactical mistakes allowing for defeat.
It was the perfect storm of the right place, at the right time, with rolling nat 20s.