Steve Young was a running QB that people said would have his career end doing that. Ironically his career ended on a hit in the pocket. Blind side hits in the pocket are far more dangerous for QBs than what they take on rushing plays because it's a lot easier to protect yourself when you see the hit coming.
Lamar Jackson also ironically just got injured while in the pocket.
https://www.youtube.com/watch?v=YOjvmxQmcS0 So I don't even know what this take is about. That injury happens regardless of him being a running QB or not.
I think running QBs hit a wall and fall off because their athleticism fades, as is the case with Newton and Wilson. Once the athleticism go's they are just lesser talented passers who are no longer serious rushing threats. It's not really about injuries because they are still far more likely to be injured in the pocket than they are running.