It seems the WW1 doctors got it right the first time.
The concern itself was right to have, but I don't think the concern has ever gone away.
So I don't characterize that as very "right the first time".
Not at all. It might be a cause, but tons of PTSD has nothing to do with concussive trauma, so much so that the other cases overwhelmed the correlating cases when they investigated the causation.
PTSD is a different thing from TBI/CTE, overlap or not. The diagnosis for PTSD was called shell shock. They did not have it right in a general sense.
one of the major problems with such weapons is that although the support crew can shield themselves, often the firing soldier cannot due to operation of the weapon.
[0]: https://www.nytimes.com/2023/11/26/us/military-brain-injury-...
Handguns and rifles make loud popping noises. Exploding artillery shells are concussive bombs that produce brain rattling blasts.