well, my comment was meant to be slightly humorous, but if you like, one could argue that the two party system gives a necessary coherence and stability to a massive, multicultural population spread out over an entire continent with vast geographic and cultural differences. not to mention that 150 years ago the country was consumed by a near catastrophic civil war. these two parties also seem to be able to assimilate the issues and concerns presented by smaller parties (i.e., the Tea Party being absorbed by the GOP, though now at apparent great cost), so real changes in platform and positions can and do happen.
there's also the issue that there hasn't ever been a remotely credible third party candidate (Perot is the gold standard here), nor do third parties bother to do much beyond run for president. it seems that many those attracted to third parties -- aside from those who might be at present unhappy with their party's nominee, but have a long history of voting for the two parties -- like to complain about not having a choice but then do little to actually create a viable alternative choice, and then turn around and not vote and blame the system. it's difficult to run for state and local offices, but that's the kind of groundwork required to create a political party.
Johnson may not be an idiot, and he may have had a brain malfunction (all that THC!) but running for the presidency does require one to have a basic minimum knowledge of current events. given that Aleppo has been gassed with chlorine and this was headlines yesterday, one would think that it would have rung a bell.
Reports of a Chlorine-Gas Attack in Aleppo - The Atlantic
i watched this as it happened, and it was in no way a gotcha question. and it was far more basic than, say, someone quizzing GWB about the name of the prime minister of Pakistan (something he also should have known, btw).
Johnson seems to encapsulate the problem with third parties -- it's difficult to take them seriously, because they don't seem to be serious about actual policy.