With the Left there is no concept of personal responsibility. Therefore they blame the tool used, not the people who do the shooting.
If the Left took responsibility for ANYTHING they caused, in particular the moral and ethical breakdown of our culture then maybe there could be some meaningful dialog regarding why this sort of thing is even happening at all.
But with the Left there will never be any sort of meaningful dialog. Not on rage killings, not on the impending bankruptcy of our nation, not on any real solution to anything they have caused. The Left will always blame other and "things" for the problems their worldviews and policies cause and then to restrict other people's freedoms as their only solutions.