The neck strength thing has.... First off, data. If you do a cross-sectional study of high school athletes, neck strength will predict the likelihood of concussion in the following year. That's an older study now, and we were all enthused when it came out because we thought the trials would be under way to prove that neck strengthening can prevent concussion. They had a lead time on the exercise trials. We have no data yet on neck strengthening having any effect for subsequent concussion. We're all still waiting.
On April 3rd, 2019. See this statement in context.