Amok and mass attacks as a separate mental illness

(This is a bit of a niche topic and I doubt it'll get much interest, but I had some thoughts I had to spew somewhere. Some weapons grade armchair psychology here, so take it with a grain of salt. I'm an enthusiast but not an expert.)
I was recently considering the idea that the phenomenon of mass murder might often be the result of an independent mental illness and not that of other disorders an attacker might be diagnosed with. For background, "amok" is a term derived from the Malaysian meng-âmuk, refering to an attack in which "an individual (often male), having shown no previous sign of anger or any inclination to violence, will acquire a weapon (traditionally a sword or dagger, but currently any of a variety of weapons) and in a sudden frenzy, will attempt to kill or seriously injure anyone he encounters and himself." This is generally considered antiquated, but not before making an apprearance in the DSM-IV as a "culture bound syndrome." However, it is not culture bound: the amok description serves as an almost perfect description of hundreds of attacks around the world, from Chinese mass stabbings to American mass shootings to familicides. The form they take differs: the presence of such incidents do not. I'm unsure how to quite phrase my thoughts, so bullet points are as good a way as any:

Some evidence against amok as a separate illness:
- It oftentimes occured in radically different circumstances, by radically different psychological types. These feature different behaviors, attitudes, and attack types (from policemen to teachers to eight year olds, from blatant schizophrenics to seemingly sane individuals, from primarily suicidal to primarily homicidal ideation.)
- It can be compared to suicide, which, while a specific symptom, is not associated with any particular disorder and can occur as a result of unbearable depression, anxiety, OCD, other mental illness, or financial / legal / personal troubles. Despite the universal phenomena of suicide, there is no "suicide disorder."

Some evidence for amok as a separate illness:
- If a disorder (say schizophrenia or depression) was not widely acknowledged to exist, incidents of it would be viewed and explained away using accepted disorders or simply brushed off. This is exactly the case for mass attacks - blame is put on other disorders that oftentimes fail miserably to adaquately explain the behavior or ignored entirely as "snapping."
- A good argument can be made that within the current understanding of the relationship between mental illness and indiscriminate violence, such incidents cannot be explained. Many attackers cannot even adaquately explain their own actions, often having a perspective of "I had to do it," which does not align with their generally low level of mental impairment. Instead of turning to complicated pseudosolutions, an amok disorder would best explain the universal manifestation of this behavior, it's inexplicable nature
- A hypothetical amok disorder could be explained in terms of a biological or psychological malfunction (perhaps an aggressive or self-defense instinct kicking into overdrive.)

Some miscellanous thoughts:
- Such an amok disorder must not be assumed to be responsible for any mass murder, especially those that are already well explained (ex. family annihilations to prevent witnesses for robberies, ideological terrorism, some arson attacks, etc.) For the purposes of this post, amok can be vaguelly described as an attack by an individual targeting anyone and everyone with practically universal hostility without strong religious, ideological, or practical justification, and generally without hope of surviving or escaping arrest.
- Amok-style attacks have occured throughout all of recorded history, all over the world. Even if their current manifestation in the form of mass / school shootings is the result of a cultural narrative as many claim, this changes only the form they take, not their occurence. Take for example the 492 BC school attack by Kleomedes of Astypalia and the 1696 Yoshiwara spree killing.
- Japan has an analagous term similar to the Malaysian amok: kireru, "a sudden explosion of individual violence which can sometimes result in a bloody act rocking the public opinion" (I've seen it used in reference to Tomohiro Katō.)
- I've been thinking on this for a while, but some of the readings that's shaped by opinion on the concept are available here and here.

dyonqqr wrote:

- Such an amok disorder must not be assumed to be responsible for any mass murder, especially those that are already well explained (ex. family annihilations to prevent witnesses for robberies, ideological terrorism, some arson attacks, etc.)

Actually, there's increasing professional opinion that suicide bombers and lone wolf terrorists are actually quite similar psychologically to conventional rampage killers in developed societies. This page contains a few academic papers on the matter, but most are behind paywalls. However, four different open source articles include a psychological profile of Mohamed Atta , several homegrown jihadists, Breivik, McVeigh, and Roof, and even al-Qaeda leader Osama bin Laden himself.