If you place killing an ideal beyond implementing your own you're making exactly the same mistake.
The best we've come up with is to try to ensure people are educated and well informed and only a majority can make certain decisions. Not all countries are doing too well on all 3 (heck the U.S. doesn't even manage to ensure decisions require a majority) but if an ideal gets accepted under anything resembling those conditions then killing the bigots is no longer an option.
Agreed, but I am sad that they don't choose to share any of those personal experiences that they claim are vital for understanding communism.
Even if communist revolutions tend to fail for the same reasons most revolutions fail (a need for temporary authoritarian rule followed by fumbling the succession) anything that can help understand how and why something failed is useful.