First off "already determined" wasn't about predestination or the future but conclusions for thinking as the exercise.
There is so much wrong with that post it isn't funny - putting aside that it looks like the rant of an archtypical Neal Stevenson character on the fence who gets seduced into the service of a regressive ideology doomed to failure. There is even the same failure to accept change and anxiety over growing old in a different world.
Culture is a Ship of Theseus, period. Even the staunchist traditionalists fail at it fundamentally from the outset because they either seek to keep stagnant what were reforms in the first place or they seek to preserve that which didn't exist even back then. Nothing makes it through the Millenia untouched. A culture which never changes is best known as a dead one.
Do you lament and blame Christianity for destroying paganism? Consider pants barbaric? Consider those from temperate climates too stupid to be civilized? What you either consider that list batshit insane or recognizd the references? Congratulations you have already destroyed a great culture spanning thousands of years already. Except we know these details. Traditions dying out is in no way comparable to losses of archives.
The description of modern European languages cultures and clothings even with the tech difference obscured would beconsidered vastly implauisble by Romans. The languages would be like a bad fanfic.
Also the communists undermining monks with eastern mysticism before Karl Marx was even born! This ridicule is being charitable for it forgets the Protestant reformation, a reaction to corruption within the Catholic church, and their role in destruction along with cynical nobles looking to seize monk maintained properties.
Ones once entrusted to them because the godly celebate were assumed most trustworthy akin to the role of Court Eunuchs among hereditary dynasties but with the emasculation kept symbolic with tonsures. There is a reason for that. While there may are differences they are based on the same.
That Western Civilization was considered a separate entity is a flaw. The concept at its best was a post-hoc explanation for rise to colonial dominance that accidentally paints things in in and out groups. At worst it was deliberate.
Marx himself demonstrated some nonsensical ideas of the day about "Asiatic Tyranny as being a more controlled society centered around artifical control of irrigation water instead of force of arms". Showing that the exoticism is continuing an old tradition of consciously or unconsciously using the exotic as a mirror to project what ifs onto.
It is like Neopaganism in a way - historians are interested in how they were but most practitioners make it fit to their world. You don't see any
They were always interconnected beyond any tidy sections or categories on maps. The people of the past sure as fuck didn't consider themselves to have a special kinship over those further abroad - hell pre-nationalism they were likely top enemies.
It also explains why the "center of Western Civilization" is all over the place with no remotely consistent metric as it is a sharpshooter's fallacy.