There is no fatal flaw in the system, and I don't why you assume it's harder to hold a single party accountable than multiple parties. Furthermore, the Communist Party of China is structured fundamentally different from western parties that are completely insulated from the public. The party in China is a grassroots party https://news.cgtn.com/event/2021/who-runs-the-cpc/index.html

The fact that people in the west have been brainwashed into thinking that voting is the only viable political action is absolutely surreal.

That's not really accurate, the Communist Party of China is just the main party of China. There are 8 other parties, and rather than competing for office, they work together and advise the CPC on different matters.

Moreover, the "two-party" system requires revolution to overthrow anyways, it doesn't have that as an advantage over China's form of Democracy.

Wake me up when any party in USA is held properly accountable for all the crimes against humanity they commit.