Great, what does that look like in practice? I'm not suggesting getting rid of or reducing access to semi-automatic weapons because I have a personal dislike of guns (although I admit I do). I'm suggesting it because it's such a brain dead obvious lever to pull when the problem is that any mentally ill person can buy a device designed to effortlessly kill hundreds of people in minutes. It's not just that it "can" work. It's that it obviously would work. Again, as evidenced by every single developed nation in the world.
This hypothetical language is so frustrating. Because all it betrays is a resistance to solutions that would stop these tragedies from happening again. I cannot fathom what the source of that resistance is. At least not when weighed against the alternative.
"Testing, training, benefits and marketing (especially testing and training)," sound great as alternative methods of reducing the problem. But again, what does that mean in practice? Why has there been such resistance to implementing even these solutions? They don't ban guns, they don't "disrespect" gun ownership, but even common sense measures like expanded background checks and gun bans for people on terrorist watch lists have been impossible to pass.
You seem to be painting the "ban all guns" crowd as intractible. And you're undeniably right in some cases. But at least their solution will definitely have an impact. The "my cold dead hands" crowd are equally intractable. And their inaction will definitely lead to more deaths.