I agree with a lot of what you write so voted you up.

Yes, historians and political scientists i.e. academics have a hard time accepting what the Nazis truly were, that's my core thesis ;)

Nazi-ism certainly has fewer books at its core than communism, however, I don't think this is any substantial difference for two reasons:

1. It does have substantial written material laying out its ideology, namely, Mein Kampf and other books and pamphlets written by Nazis. The idea that these books are less intellectual than Marxist literature is an idea propagated primarily by, well, academic types. There's no substantial difference in terms of the robustness of their core ideas or longevity of their insights.

2. The obvious reason the Nazis wrote fewer books is simply that they didn't need to: they seized power far quicker than Lenin did, and they had the benefit of access to modern technology like radio. Hitler did on the other hand produce prolific quantities of speeches laying out the 'intellectual' basis of the ideology, which is what you'd expect for someone who was around nearly a century later. After all, Stalin was no great writer either. The communists produced the bulk of their output before they seized power.

This seems to elide the obvious places where they would be different, viz., the sort of society they wanted to build

What sort of society did they want to build, exactly? Strip away the decades of academic obfuscation and you find Nazi-ism and communism are nearly indistinguishable. They both were totalitarian ideologies in which all power was concentrated in a dictator. They both built concentration camps at scale. They both claimed to speak for the working classes, they had the intention to dominate the world (until the USSR realised it didn't have the strength to do so and the COMINTERN became less relevant). Soviet society looked a lot like life would have looked in the third Reich had it conquered all of Europe and then been unable to go further.

Whatever it is, the latter clearly have far less institutional power within the left than advocates of the total extermination of their racial enemies did under the Nazis

I hope you are right, but how sure are you? Randos on Twitter certainly seem to wield institutional power and far more than the middle-of-the-road social democrats, whose views are increasingly irrelevant.

Obviously if you compare anything going on in contemporary society to the Nazis on the brink of defeat, the comparison will seem extreme and unhelpful. The reason these discussions matter is that if the world is to successfully avoid a repeat of 20th century history then it's not enough to say, "oops, these people are acting just like the Nazis in 1943" because by then it's far, far too late. The only hope is to say, "this looks suspiciously like the Nazis in 1933". And in that regard "randos on Twitter" do look extremely concerning.

Perhaps the author is indeed this sort of person, but in that case you could probably try finding something to cite.

This is an excellent point. Whilst we may have strong stereotypes about such people and the whole package of beliefs they usually subscribe to, is it true in this specific case?

I took a quick look at the author's Twitter account. Here [1] she claims she invented a new pronoun. There's plenty of anti-capitalist tweeting, of course. In August 2020 she retweeted a defense of trying to kill cops with Molotov cocktails [2]. In June 2020 she was retweeting her support for the removal of Woodrow Wilson's name from some university college [3]. She retweeted a claim that "White innocence makes a delicious story, and none of its beneficiaries wants to hear about how that particular sausage gets made". It takes a dig at "British nationalist myth making" for extra pop [4].

I guess I could go on, but do I really need to? The author is an utterly bog standard New York liberal who praises BLM, hates capitalism and thinks Britain is "collapsing under the weight of racism". She is a walking stereotype and as such it's no surprise at all she finds herself sympathising with the propaganda of the most racist government in history.

[1] https://twitter.com/sarasara_sck/status/1380348332560822277

[2] https://twitter.com/allisongeroi/status/1291378034616999944

[3] https://twitter.com/imaniperry/status/1276920110402461698

[4] https://twitter.com/Longreads/status/1275205428675317761