Perhaps not necessarily killing them, but making sure that they never came to power or their ideas were never implemented might be a better way to deal with these plagues on humanity. I don't know if we would have learned the harsh lessons that these people provided, though. Imagine if there were never a "Holocaust" ?? Imagine if Communism had never been a realized concept??
No Holocaust, means no Israel. No Communism, no scientists, doctors, that led to Sputnik.
No Civil war in America, the blood and suffering never was. Darn I am glad I was born to white folks in New England, I could have been born from the belly of a black slave in a slave state.
Had the Japes not declared war against us, the Germans would have developed the bomb, they were only a few months from figuring out Heavy Water.
Say the English King dropped dead in the time of our first Tea Party----who would have replaced him ? What would our lives be like today .?
Then there is the question of Jack Ruby, had he not killed Oswald, what would we know today.?
Had someone not found gold notes in a barn in the 1930's how would history have treated Charles Limbarge.?
Had a night watchman called in ill one night, there would never been a Watergate.
Had we dug the Panama Canal in another country, would we still not have found the Mayan Civilization ?
Seward bought Alaska, had he died a week before the transaction, what country would be controlling it today.?
What would have happend if Lewis and Clark could not get fonding for their little excursion west.?