I'm at work at the moment so I'll add more to this answer later.

The biggest thing to keep in mind is that mail is an incredibly time intensive labor and as such, expensive, even without considering the material costs.

This cost alone means that it was cost prohibitive for Chinese armed forces to adopt it on a large scale. On the small scale, elites and people of high status would indeed occasionally trade or make local reproductions of mail, so it was not nonexistent in China.

Chinese armed forces were often very large and preferred to equip their men cheaply.

Also, Chinese military adversaries were usually steppe people/nomads. This meant that they were focused on developing an effective mobile cavalry force as well as defensive tactics/technology for defending towns/cities against mounted raiders.

Their main worry was from arrows and as such, the average lamellar armor and silk linings were often good enough to stop arrows from penetrating.

Mail and other more expensive armor would have most likely been seen as unnecessary for the most part.

Again, the focus for many centuries was protecting the borders from mounted raiders, developing cavalry, and defense of towns/villages/cities. The other main enemy would be other Chinese forces, whether they were bandits, rebels, or fellow soldiers following rogue warlords/opposing sides in civil wars.

Either way, for the average levy in the Chinese military, mail would have been seen as excessive and too costly.