If you made some factual statements rather than blanket statements like "it's not debatable" you post might come across as more knowledgeable.The Fatimids having lower military tech? Why? The Europeans didn't have a technology advantage; they had a quality advantage that proved fleeting later on. The knights stemmed from a highly privileged social class that could draw on the resources of the rest of the society. But they were scarce and formed only the core of the crusades. The crusader armies had plenty of riffraff as well to fill the rank and file.
Europeans should have an advantage in Europe and on the shoreline of the mediterranean. The muslims would have an steep advantage in desert terrain and the deep inland of the middle east. Libya and North Africa, for example, should be essentially impossible for HRE and others to conquer in 1066.
In the 1066? No it isn't debatable. The muslim empires had made siginifcant agricultural advances by that time, which weren't well known in Europe. And agriculture was like 95 % of the economy at this time, so these advances had real effects. Cultural advances depend on the eye of the beholder.
Military technology (in the game) means: Refinement and effectiveness of weapons. Western Europe in 1066 looked back on a history of over 200 years of incessant warfare against all kinds of fellow Europeans as well as invading people. Warfare was the defining feature of its ruling class. The knights that barged into the Levant in the first crusade might never have seen soap, bazaars or water toilets, but they were pretty damned good at KILLING PEOPLE (which is 90% of what warfare is ultimately about)
The discussion is about how to "fix" the Fatimids i.e. make them less overpowered. It doesn't really help the issue in any way if you debate the social background of knights or their relative numbers in a crusading army, unless you propose how any of that connects to the game. Sure the crusading armies had riff raff but what is it that you're saying? That the light infantry should be weaker? Stronger? Left as it is?
I think Egypt and the middle east in general needs a bit of the nerf hammer... it's okay to have scary muslim bogeymen in the game, who can defeat even an intact Byzantine or HRE empire, but from a game design standpoint it's just really awful if they start out as mega threats on day 1. That's really the gist of it.