[pensiveforns]

This is a good summary, but it's even more nuanced than that.

For example, while China did lose the Sino-Vietnamese War, they did achieve two important objectives.

First, they proved to be a trustworthy ally to Cambodia. This is why those other SEA countries like Cambodia, Laos, and others that were bullied by Vietnam are much more pro-China right now.

Secondly, they showed that while the USSR was a Vietnamese ally, it would not interfere with China.