I can point to at least one fatal crash that wouldn’t have happened if GPS was unavailable. Would it be reasonable to say that crash was caused by a lack of GPS jamming?
Something like GPS jamming isn't quite so bad. It's intuitively reasonable that reducing or degrading the information available to pilots will make things worse, and avoiding that is likely to improve safety. But it requires proper analysis to figure out the best thing to do, not a simplistic "this specific event wouldn't have happened if this specific fact had been different." That's what "cause" is about in a practical sense: not "what changes would have avoided this past event?" but "what changes improve our odds in the future?" And the first question isn't nearly enough to answer the second.