How do you define 'death cult'?
Mao killed much more people in absolute numbers.
Cambodians killed drastically higher share of their own population than anybody else.
There are much more horrifying images available from other countries...
SS officers had potassium cyanide with them only in exceptional cases.
SS consisted of several directorates: security police, intelligence, concentration camps, frontline units, etc. It was a type of security apparatus of a state. SS was very similar to Soviet NKVD that also had a directorate of concentration camps called GULAG (these two cooperated intensively and exchanged a number of practices in 1930s.) It sounds unbelievable, but the SS learned how to set up concentration camps from Soviets. Newly revealed documents from Soviet archives present simply breath taking facts!
Death camps themselves served a dual purpose in Soviet Union. Surely, it was a way of getting rid of unwanted 'them' - people opposed to Soviet rule, sexual minorities, certain ethnic groups, etc. - but these camps also served as a source of free labour. Soviets had no money to industrialise their country like the West did, so they turned huge numbers of their own people and people from occupied countries into slaves who worked until they dropped dead. Sounds no different from Nazi Germany, does it?
As you see, it is the racial hatred combined with economy and organisation of society that produces practices attributed mistakenly only to the Nazi Germany.
Was Soviet Union a death cult? Communist China? Communist Cambodia? They were not, they were extreme forms of a nation-state based on juxtapositioning of 'us' (belonging to one ethnic, political or other group or race) to 'others' (belonging to another ethnic, political or other group or race). Take such an opposition to the extreme, and you'll end up with breeding programs, concentration camps, etc.
It is the usual trick one's ethnic identity plays with the mind.
My claim above was that such a thing could happen even in the nation-states that consider themselves being democratic and tolerant. They may say that they have got over the 'us'-'them' separation, but they have not. In fact, their whole identity is based on that and there are no guarantees that when that identity is threatened, uninhibited violence will not be unleashed. Various anti-immigration political movements are an indication of threatened identity.