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.