1. My argument was about "National Socialism and any other ideology out there", you focused only on the first part. Even if you filter out unethical ones (not sure how, but let's say you can), there would still be too many to try, and not sure why should we keep trying theories instead of letting the society evolve in a natural way.

2. Specifically about giving communism a fair trial despite all past failures because it is "ethical": no thanks. I find its principle of "dictatorship of the proletariat" unethical and proven disastrous.

3. Stalin disappearing his political enemies was rooted at least in part in Lenin's cornerstone principle of "democratic centralism" which was critical ingredient for the success of the communist revolution. Trying to decouple the two doesn't do history justice.