I'm not the person you're replying to, but I think you missed the whole point of GarbageShoot asking you specifically about Allende.

just based on a small snippet of reading about them, I think in general [...]

I think this is the main problem here: a lack of knowledge about the historical context of "authoritarian" socialist projects, but nevertheless making generalized statements about them without even considering the material reasons why they were by necessity "authoritarian." Read up more about the history of Chile and consider what happened to Allende and the hope of a socialist Chile. Who came after Allende (and almost as important, who installed that successor)? Why do these events seem so familiar when learning about every other attempt, successful or not, to bring about a communist society? When you've done that, you will at the very least have a leg to stand on when criticizing so-called tankie authoritarianism.

I'd also suggest reading The Jakarta Method. Here's a somewhat relevant quote from it:

This was another very difficult question I had to ask my interview subjects, especially the leftists from Southeast Asia and Latin America. When we would get to discussing the old debates between peaceful and armed revolution; between hardline Marxism and democratic socialism, I would ask: “Who was right?”

In Guatemala, was it Árbenz or Che who had the right approach? Or in Indonesia, when Mao warned Aidit that the PKI should arm themselves, and they did not? In Chile, was it the young revolutionaries in the MIR who were right in those college debates, or the more disciplined, moderate Chilean Communist Party?

Most of the people I spoke with who were politically involved back then believed fervently in a nonviolent approach, in gradual, peaceful, democratic change. They often had no love for the systems set up by people like Mao. But they knew that their side had lost the debate, because so many of their friends were dead. They often admitted, without hesitation or pleasure, that the hardliners had been right. Aidit’s unarmed party didn’t survive. Allende’s democratic socialism was not allowed, regardless of the détente between the Soviets and Washington.

Looking at it this way, the major losers of the twentieth century were those who believed too sincerely in the existence of a liberal international order, those who trusted too much in democracy, or too much in what the United States said it supported, rather than what it really supported -- what the rich countries said, rather than what they did.

That group was annihilated.