Quote Originally Posted by Carry2 View Post
Though, in that case, it's hard to see how they wouldn't rapidly outstrip the imperium in the tech arms race. Hmm.
The Ork's understanding is largely genetic, which means that each generation doesn't learn so much as gradually gains access to increasing amounts of premade information (thus why pretty much all Orks have certain types of vehicles and tech, despite being galaxy-wide.)

For example, Flash Gitz represent the pinnacle of Shoota technology. They understand it as much as anyone ever will, and they won't pass on their knowledge to the next generation because the next generation will simply grow up to be Flash Gitz. In 80k, the Orks will not have bigger and flashier guns, except by looting Tau weapons.

Also, it is possible to avoid warp possession through faith and willpower, and the Ork's faith in Gork and Mork is unshakeable.

It's also worth noting that the Eldar only have to be super careful because there's a chaos god waiting specifically for them, who has a unique bond with them. Pre-Slaanesh, they were a race of latent psykers that didn't live in constant fear of daemonic possession.