I remember when Abbott's government cut the budget for mental health and within around a month it seemed like the homeless population in the CBD doubled.
Media contagion. People on the edge see news coverage about an event and "get inspired" by it.
A classic example of media contagion is how after wall-to-wall coverage of Curt Cobain's death suicides spiked. This led media organizations to police themselves when it comes to how they report on suicides. Those guidelines still exist and are (usually) voluntarily adhered to.
There are solid arguments (and ongoing research) into media contagion driving mass shootings and other acts of violence. In fact, it is widely cited as the reason why people who wanted to commit public attacks switched from bombings to shootings after the media coverage of the Columbine shooting.
There isn't a healthcare system in the world that can cure "driven to murder multiple people". The pro-gun community blames "mental health" not because it's the root cause but because it will take 100 years to fix.
After 20 years of scapegoating things they find undesirable (like video games, gay marriage and music), they've finally blamed a few things that are at least contributing to the problem but ultimately they're being just as dishonest as they've always been.