What is strange? The complete failure to imagine anything other than capitalism, communism, or fascism, to think outside "things we have already tried" despite the observation that the things we've already tried all suck.

I think you're projecting; it's by no means a mutually agreed observation that these things all suck. Plenty of people think that capitalism is great. Some, despite the evidence of the past century, still think communism is great - the author of that quote, Slavoj Zizek, prominent among them. And while few openly call themselves Fascists, there's actually no shortage of people holding views that fit broadly in that spectrum.

To change your analogy:

Alice: Chocolate ice-cream is the best.

Bob: No, vanilla is the most delicious.

Eli: Look, we're all agreed that chocolate and vanilla ice-cream both suck. So let's all try pistachio!

A&B together: No!!!