It is about the weapon. If someone wanted to inflict a lot of damage, they would use bombs. That has happened several times in the past but doesn’t compare to the number of mass shootings. Why? Because guns are simply just plentiful and easy to get, and too many apologetics keep allowing them to be plentiful. It really is that simple. Yes it doesn’t fix society’s underlying issues but that is a MUCH harder problem to solve than simply getting rid of (as many) guns (as possible), or at least not just allow so mamy people to own them willy nilly.
The goal is to drastically reduce the number of innocent lives being taken ASAP, not to argue about weapons or social ills or all of this other nonsense.