What's your definition of "isolated issue"? Most people use it to mean a random one-off that isn't part of a pattern, which can't reasonably be applied to mass shootings in the US at this point.
Mass shooting and terrorist atacks are still extremely rare events, very much like plane crashes, compared to the many other ways one could get killed or injured.
I agree that mass shootings aren't a large statistical risk for an individual. I'm only objecting to the use of language that suggests they aren't a systemic issue.