That's a really interesting article, Etmoi. What she is clearly describing is a cult, yet she never actually uses the word cult, I wonder why not?
There's an interesting series on Netflix called "How to become a cult leader". It's quite odd in the way it approaches the topic with animated segments and a kind of jolly tone, but each episode examines a different cult, how it started and developed, the characteristics of the leader and so on. It looks at the Moonies, Heaven's Gate, Charles Manson, the one that was responsible for the sarin nerve gas attacks on the Tokyo subway and others and what they all have in common. There's another related series which is "How to become a tyrant" about Stalin, Saddam Hussein, Gaddafi, the Kims in North Korea and so on where the parallels with the cult leaders are obvious. It's definitely worth a watch to get your head around this sort of thinking.
This bit from your article is the most obviously cultish
"Your world shrinks to a succession of meeting rooms in which your dear, witty, intelligent comrades periodically accuse each other — and sometimes, devastatingly, you — of capitulating to the bourgeoisie. You survive your victimisation, barely, and await vengeance by becoming one of the accusers. It is quite sick. Yet the beating heart of this toxic cycle is the most fervent and loving dedication to humanity found this side of sainthood."
We see this sort of purity spiral playing out all over the place on the left. The trans debate on the left is another area where speech is so heavily policed and free thought stamped on. Lots of feminists have found themselves cast out or brought to heel over that issue (has "bourgeoisie feminist" been replaced by "terf"?)
And "the most fervent and loving dedication to humanity found this side of sainthood" is exactly why people were claiming that Corbyn couldn't possibly be antisemitic. Even though he is clearly, antisemitism aside, a bit of a dick.
The author clearly still thinks that her comrades were lovingly dedicated to humanity rather than the idea of themselves being lovingly dedicated to humanity. That deprogramming may take a while yet.