I'm not saying "result" but system. The US constitution got written after the US got independent and not before.
several post-Soviet states (if you count leaving the USSR as a revolution)
Some countries of the USSR did copy the Western style of democracy and free markets. They could do that by letting other countries send people to tell them how to run their country. They didn't do that because they themselves knew how to create a democratic state with free markets.
This is trivially true if you mean that no revolution produced the desired result up to the end of time. But then, the same is true of anything any human being does.
If my project is to lock my apartment with my key, then I can be quite certain that the result with look roughly like I plan beforehand. The bigger the project the harder it is to plan everything beforehand.
As a result big software projects get these days not fully planned in advance via waterfall but get created in an agile way. Creating a substantial new political system as opposed to just copy some existing one, is much more complex than a software project and therefore even less doable via waterfall.
Perhaps a more precise point is that the first American government failed. John Hanson and the other 9 Presidents of the United States under the articles of confederation were operating the true government they threw the revolution for. It failed almost immediately -- you would be astonished at how hard it was to convince someone to run the country, hence the extremely high turnover on Presidents.
I, and many other people here on Less Wrong, live in a massive, surprisingly enduring Plan B of a government.
[It's worth pointing out I like this one better, because we can find appropriately qualified staff, which is, ya know, pretty good. But alas, I was not a father of the American Revolution.]
Another month, another rationality quotes thread. The rules are: