None of this rings true to me. I've never heard or read anything like "it wasn't the perpetrator's fault, it was XYZ", but rather "it was the perpetrator's fault, and I wonder if XYZ contributes to the prevalence of such perpetrators". In the US at least, there certainly appears to be something going on outside of random happenstance[0], so it makes sense to think and talk about what that may be. Certainly many people use such things to rail against their pet cause, but far more people are just trying to figure out where we're going wrong.
I think the difference is people spend relatively little time on the perpetrator having some propensity to have issues (as will happen to some people when you have 7 billions-strong-bell-curve of them) and a lot of time on what could have triggered/exacerbated their issue (which could be a lot of things that don't cause issues in most people). For example, video games, pot, guns, etc. which don't cause issues in most users but seem related to issues in some users. This leads to an over focus on banning the thing most people use without issue rather than recognizing the statistics of 'out of 7 billions people some will have issues'.
As argued in the article I linked (and elsewhere), the U.S. in particular appears to be a statistical outlier, which suggests that we might be able to identify what is different in our policies, and make some improvements.
[0]: http://www.charlespetzold.com/blog/2015/07/De-Obfuscating-th...