Just like programming languages can only have two out of three concepts ( soundness, completeness, decidability ), the creators of the internet had to choose two out of three concepts ( openness, robustness, security ).

It's theoretically impossible to have a language that is sound, complete and decidable. It's probably also impossible to have an internet that is open, robust and secure.

I don't think that argument holds water.

Which one of "open, robust, secure" do you think Tor doesn't meet?

You can pick any 3 concepts and group them together like that, but it doesn't mean you can't have all 3, e.g. a house can be "large, cheap, and well-decorated" (e.g. if it is in the middle of nowhere).

How does one use Tor without the internet?

Tor lacks usability and efficiency.

The efficiency isn't as bad as it used to be. I browse using Tor as a matter of course now, and it's fine.

What's the usability problem? Just that you have to download Tor Browser instead of Firefox?

The usability of setting up a hidden service is actually easier than getting an SSL certificate.

Those weren't on the list. ;-)