I find this is done universally. Every time some shooting or similar disaster occurs, the actual perpetrator is among the last to take the blame. It's the video games, it's the music, it's the toxic culture of masculinity, it's the pharmaceutical drugs, or it's the Zionist media poisoning our children with Judeo-Bolshevist propaganda.
The obsession is with the "one single cause", but more importantly the opportunity for every demagogue to revel in vilifying their preferred scapegoats. Nothing gets fixed, and people wonder why.
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.
On the same token, there are many people discussing "other causes" while not removing blame from the perpetrator. For example, if it's easy for someone to gain access to (e.g.) nuclear weapons, it increases the damage that one bad actor can do. It's irresponsible to pretend like there will never be bad actors. Restricting access will never eliminate bad actors, but it's an attempt to limit the damage that bad actors can do.
Example of this abound. Let's take the corrupt cops. Not every cop is corrupt, and the police as an institution is (by many) considered a good thing. Corrupt cops are also responsible for their own actions.
On the other hand, corruption / bad actions on behalf of the police, while not necessarily "rewarded" is usually only met with wrist slapping. In one instance that I can recall, a police office was caught on tape offering accept sex as payment to make an arrest warrant go away. Said officer's punishment was just to get fired. How many police officers in Canada have been punished as a result of the G20 debacle or the handling of the Vancouver Olympics security? What about the trigger-happy LAPD[1]?
Society has some blame if they impart a message to would-be perpetrators that the consequences of bad behaviour are not very severe.
That's an interesting take... It's like the perfect storm of our collective tendency to shirk responsibility, our tendency to generalize in search of a single unifying class, AND the tendency for powerful bodies (governments, corporations, or individuals) to re-contextualize any issue in a manner that validates their operations.
The obsession is with the "one single cause", but more importantly the opportunity for every demagogue to revel in vilifying their preferred scapegoats. Nothing gets fixed, and people wonder why.