"Nazism" in today's usage is a collection of ideas (many with some ressemblance to the ideas of 1940 Germany). The label "nazi" is applied to anyone who believes any of them.
The biggest reason why holding one of these ideas makes it likely you'll hold the others are the effects oulined above (people being pushed into the wotch community). So, in essence, the modern censorship environment created the modern Nazi. :D
And how do you explain the correlation in the past? Because the correlation of these ideas is not modern development, it was like that already during Nazi era - and when before it.
And in fact quite a few of your examples in fact are part of that ideology.