system
Given the following post, respond as if you're commenting on Reddit:
human
[ASoIaF] Why is the linguistic diversity of Westeros so limited?

From north of the Wall to High Garden, all the people of Westeros seem to speak a mutually intelligible language, no matter if they are a northern noble, a Flee Bottom gutter kid, or a wildling. This seems strange, as Westeros has no of the institutions that encourage language homogenization, such as centralized government, highly literate populace, and widespread written word.
gpt
Actually, Westeros is better equipped than anywhere else in the explored world for language homogenization for one institutional reason: the order of Maesters.

These learned gentlemen serve many purposes throughout the realm, one of the most important being providing a standard service for all the great lords and many of the lesser lords of the land. Among themselves they use a standardized version of the Westerosi tongue, and it is from them that the lords learn their letters and grammar, and it seeps its way down to the smallfolk from there. After all, you can't very well ask your lord for a boon if he can't understand you.

North of the Wall, many of the southern wildlings speak an approximate version of the common tongue, and this is because they still have some measure of commerce with the Kingdoms. Men of the Watch run away, raiding parties steal women, and there is even trade with the Watch from time to time. The tongue is kept alive this way. However, the farther north you go, the less intelligible it becomes, and in the far, far north the Thenns and other groups speak the Old Tongue that was said to be that of the giants and other creatures that we know to be extinct.

It's the Maesters that we have to thank for our standard of living, as their studies press us forward in language, agriculture, economics, and every other field of study that the order pursues. The Great Chain pulls us all.