Basically actual military people play the game too (just like how commercial pilots play flight sims as a past time).

The devs go as close to real as possible but of course with still in-service vehicles that’s not always possible.

So sometimes people leak classified information. I think it comes down to:

1, bragging and forum debates going to heated (I know this info!)

2, actually helping the devs

3, “being a gamer” = this vehicle is weak but I actually know it’s more powerful so I prove it

Maybe they're trying to establish themselves as a place to leak military secrets.

Access to that particular material and that particular doc might allow the set of possibilities around a suspected spy to be reduced until there is only one person in it.

The information was previously available on the net and was accepted by consensus for most of the PLA watching community, but there was no really hard evidence.

the latter, people really can't stand to lose internet arguments :)