I would pose that Hitler, outside of his involvment in WWI, never killed anyone, at least I can find no evidence of such.
1. You fail to note that there were three distinct factions in the Khmer Rouge:
a. The nationalist and racialist group headed by Pol Pot, Ieng Sary, Son Sen, their wives, and Khieu Samphan, who wanted to carve out Kampuchea's own original communist society, not patterned on Soviet, Chinese, Vietnamese or any other models. They were inspired and strongly influenced by Maoism and by the Chinese Cultural Revolution. However, they secretly despised the Chinese leaders. The group most opposed to Vietnamese expansionism and immigration. (Nationalist group)
b. The group headed by Hu Num, Hou Youn, Phouk Chhay, and Til Ov who fought for applying the model of the Chinese Cultural Revolution to Kampuchean conditions. (Semi-nationalist, semi-internationalist group.)
c. The group headed by So Phim, Pen Sovan, Keo Moni, Chou Chet, and others who favoured building a socialist Kampuchea by following the Vietnamese model. This group was comprised mainly of veterans of the Khmer faction of the former Indochina Communist Party and those who supported their internationalist positions. Supported Vietnamese imperialism. (Internationalist group.)
Now, each of these groups had its own bases and power centres: Pol Pot initially in the northeast among the Montagnard tribesmen; Hu Nim in the south and soutwest in the Elephant and Cardomom Mountains; and So Phim in the densely populated eastern provinces between Mekong River and the frontier with Vietnam.
Now, how can you blame all of the killings which occurred in that time on Pol Pot himself?
2. Show me a scrap of evidence that Pol Pot approved the killings. After all, most of the time lived in an ivory tower in Phnom Penh, the capital of Democratic Kampuchea; the rest of the time whenever he visited the countryside, the visit was already planned ahead of time.
3. No one is responsible for what someone else did, especially when it comes to such a thing as killing.
Yes, history does matter.
I highly recommend you to read the literature on Pol Pot and the Khmer Rouge from an intellectual perspective, properly and comprehensively to understand the reality of the actions and results of the actions of the plans of Pol Pot as enacted by the Khmer Rouge. The most comprehensive book on this subject is Ben Kiernan's book titled "The Pol Pot regime : race, power, and genocide in Cambodia under the Khmer Rouge, 1975-79". Even though it is inherently biased it still provides facts and the emotional opinions of the author are obvious rather than mixed with the fact to distort facts.
At the risk of feeding what I think is obvious trolling compounded with Goodwin,
Why do you have to provoke a flame war without being provoked to do so?
By the way, weren't you the guy that used to have Chomsky in your avatar?
Chomsky supported the the Khmer Rouge while they were in power.