Do you really have to pile on three at once?
We could make it four. 
Good job. We just got distracted by the shiny OP. Thank you for doing our heavy lifting.
Kip Kinkel (not “Krinkel”) has schizophrenia, not an anger management problem. His sister does not have schizophrenia.
Thing is there are plenty of schizophrenics who don’t go on mass shootings. In fact mentaly ill are more likely to be victims than perpetrators of violence.
Well, I mostly notice it only when my brilliant posts get ignored.
Mostly.
You’re talking forests and trees there.
That’s a bit of straw man argument. As far as I can see no one is saying anger management has to be a cure-all 100% guarantee or it is useless.
It should however stand up to the same scrutiny as any other treatment, be it a therapy or a new antibiotic. Has anyone shown (statistically, using valid scientific methods) that anger management therapy makes people less likely to commit violent crimes than people who have not had the therapy.
The instances you mention are more closely associated with mental illness than simple anger problems.
A couple of addenda to add to the better answers above…
things like “anger management training” have to be done CORRECTLY. Listing out example after example where court-ordered “therapy” failed, and declaring that this proves that it’s ineffective, is false reasoning. It isn’t valid data, unless you show that in each failed case, that all the steps were done well and thoroughly followed and tested.
First hand example: one of my sons was caught DWI, and had to go through a number of court-ordered “therapies” to deal with his drinking. Several of the “courses” were offered by what you might call “professional court-pleasing” companies. That meant that they put all their REAL money and effort, into taking roll each time the class was held, and making sure each “pupil” nominally followed the steps in the program. My son ended up being of the opinion that the real purpose of the courses, wasn’t to help him, it was to make sure that he paid four times the official fines (since he had to pay for his “therapy”).
Similarly, the court system and the laws have to be “done correctly.” Too often, the laws are passed in order to fulfill another legal or political concern, such as a requirement to do something other than sending everyone who messes up to prison, or letting them go and repeat their messes. The law establishing anger management as a sentence might have passed and been applauded, but if the budget in the next bill fails to find it properly, it will be another fake program, and wont help anyone.
I fix machines for a living. Done it all my life. And I know VERY well, that if the fix-it guy skips steps, uses the wrong parts or cheaper ones than they should, the wrong lubrication, worn tools, and so on, the machine wont work when they are done. That doesn’t mean that “repairing things doesn’t work.”
If he hadn’t killed his parents, they too would have been incarcerated, and probably still locked up, because they purchased all those guns for him.
MHO, of course.