system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] Peter Quill can understand the rest of the guardians due to a translator chip in his neck, but it doesn't translate Groot. However, Rocket and Thor both speak Groot, so it's clearly a full language. Why does the translator chip translate every alien language except for Groot?
gpt
Groot is among the last of his kind, his homeworld was destroyed. Most likely no one has ever bothered to make a translation program for it. So Quill wouldn't have it loaded into his chip. 

Rocket knows it because he's learned it. Thor knows it because Groot's people used to be more prominent in the past.