Why should thousands be reduced simply due to some lone nut? Gun bans would not have stopped this, as one the guns was a shotgun often sold for hunting.

The problem is a more effective solution to the problem of lone nuts would need to see privacy reduced to enable the government to check on people who are reported as being at a breaking point. And then you’d need the return of involuntary commitment, in some cases long-term, for those at such a point. That idea, though, would be even less popular since it would be necessity be invasive, and would likely be in some cases abused.