Now, let's say they try to sell me an application that they haven't written yet. But it'll be fine, they say, because they've decided not to use Brainfuck though they won't divulge what they will use.
Exactly how unwise would I be to dismiss them? I mean they might produce Utopian software next time. But is it really wise to assume so?
Don't assume, get out there and take a look if you're interested. But if you're not interested, there's no need to draw up strange analogies as if they discredit a whole massive field of literature and research going back to the fall of the USSR and even before that from internal resistance (such as from Orwell, Einstein, the leftcoms and anarchists) within the USSR. Even Lenin recognised the differences in ideology, famously allowing a funeral procession for anarcho-Communist Peter Kropotkin to continue, despite his supporters being vocal opponents of the Bolsheviks. And what of the Mensheviks, too?
There is too much to dismiss, at least in my opinion. Though I admit that if we want to continue with Marxism-Leninism, a specific variant of Marxism which is a specific variant of German Socialism which is a specific variant of Communism, then we should investigate that. If not, then we shouldn't dismiss the rest of Marxism, the rest of Socialism and the rest of Communism, anarchism, egoist anarchism and even post-left (Stirnerite) anarchism, or even Georgism or social democracy. If you're going to start dismissing Communism, where do you stop with it?
It's also worth noting that almost all the states you are referring to as monarchies or oligarchies are founded on the principle of Marxism-Leninism. Perhaps this isn't the best way. Left-Communists agree with that idea. Or perhaps anarcho-Communism is a better idea.
There are many schools of thought within Communism. It's unwise to dismiss it, in my opinion.