I don't necessarily disagree with your main point.

Though the arguments you make will not work on anyone who doesn't already agree with you.

You kinda cope in there by saying that the governments that called themselves socialist in the past were democratic, which is kind of not true for a lot of them. There's degrees to it but for the most part they weren't.

I think it's smarter for us to distance ourselves from those governments as they ultimately didn't really represent our views, not mine at least.

The other problem is the Engels On Authority ass first paragraph, equating use of violence with authoritarianism.

When you do thay you kinda just come off as an authoritarian if people aren't already familiar with your definitions (similar to using the phrase dictatorship of the proletariat.)

The argument is also just silly and I wish I could go back in time and stop it from entering the material world but I am too lazy to write about it. A lot of libertarian communists have written about it over the past century so you can probably fish something up if you look.