“Greece” extended from Sicily to Afghanistan to Egypt. Hellenization incorporated a lot of different people. Then Islam incorporated a lot of different people.

Because you'll be bombed or shot or invaded if you try to assert the authenticity of non-Muslim, non-Arab identities being native to the Middle East and North Africa.

Lol tell it to the 20th century, bud. They were fine with not executing a cultural genocide only as long as they could hold it over other groups that "we brought you Islam". Once Islamic empire stops being the unifying political force, all of a sudden you get pan-Arabism: Kurds and Imazighen have their languages banned, Jews are thrown out of the country, etc.

This is history as written by Europeans*, don't forget.

So the question is: why do we refer to e.g. Newton writing in Latin as an English scientist (and not Christian, or Latin) but anyone who wrote in Arabic is either an Arab or Muslim scientist. Now this may have started due to lack of information (before Europeans came to fully survey "Middle East") but it persists to this day. One can speculate to the possible reasons, of course, but it suffices to point out the pheonomena.

* Ibn Khaldun, the famous Arab historian, for example, did not have this issue (to his lasting credit):

https://sonsofsunnah.com/2011/11/12/ibn-khaldun-on-the-persi...