> That's insecurity in my book, not weakness.

To see that it's actual weakness is enough to look at a few decades of history of China for example. They had single party for a long time, but were regularly on the brink of societal upheaval and even experienced few times very large changes, with a lot of people in power suffering as a result.

Nothing like that happened in two party system. When some people in US start to feel that they are manipulated by both parties (occupy, blm) you can see how they behave. And they are met with overwhelming force until they burn out and disperse again.

> I agree, but in a dictatorship the people are held back from what they could contribute.

Dictatorships are yet another thing, different than one party system. They limit people very severely just because they don't invest in any infrastructure that doesn't directly serve the dictator. And he is just one person (plus his most important people) and has limited needs and imagination. How much people can contribute depends mostly on what tools and infrastructure people are given. Even a completely free person without tools and infrastructure won't be able to contribute much because its the technology and economy around us that makes our work valuable.

> Perhaps they seem that way from far away, but the parties can and do change their positions over time and they compete with each other to please the public.

To see the bigger picture it's better to take few steps back so you can stop trees from occluding your forest. Sure. Two parties compete, they discuss, they change their positions, they seem to respond to what people currently want. But in practice most change is driven under the hood by influence and money not by the public discussion. And the public discussion is held just to explain away things. USA has for profit prisons not because people decided. But because someone with money and influence figured it might be a good way to earn more money, and pulled the right strings in the system of power. First you see the opportunity, introduce the change and then either keep it out of public discourse or just spin it as the best thing since sliced bread.

> A single party system may also respond to the people's will but since speaking your mind publicly is forbidden, you never really know who made a given decision. Someone may get blamed for it but you won't know if they were the true decider. That's why you see the same party maintain control, the top decision makers cannot be held accountable.

Most top decision makers in two party system stay hidden and unaccountable as well. Person who decided it's a good way to publicly market opioids was not elected. And you have no idea who are the elected people who were influenced to not be interested in this subject.
If the decision turns out to be especially bad, you sometimes can find out who made it or at least who was chosen to be blamed for it because system of power drags this person into the limelight to punish them publicly. Same thing happen in single party system, where many former revolutionary colleagues had public trials for their wrong decisions (sometimes accurately, sometimes wrongly, but always very selectively, same as in two-party system).

> Mao is still revered despite causing widespread famine, for example.

What does that prove? US still reveres slave owners and native people slaughterers. Cult of Mao got stripped down a lot when Deng Xiaoping came to power. It was scaled back to the useful level.

> That's right, in a multi-party system the people can hold the previous admin responsible for any failures by electing a new party or individual. It's not so much about people needing an enemy as it is about acknowledging that all people make mistakes.

Two-party system is different from multi-party system. In multi-party system, the party that made the bad decisions doesn't get elected next time. People elect some other party offering some solutions and they have at least few parties and proposed solutions they can choose from. Offending party often has it's reputation tarnished so much that it dissolves. Politicians that formed this party need to join others, seek new alliances, come up with new ideas how to regain reputation. Actual change is possible.

In two-party system you just get few years of respite, before you are forced to begrudgingly let the offenders back into the offices and to again control your life by reverting many decisions of the other party.

> It's hard to get people to publicly take responsibility for their actions and it's next to impossible for that to truly happen when a single party rules.

Ultimately what's important is what happens, not who takes responsibility for that.

> In a multi party state, the losing party has a chance to come back and usually that involves some admission of error, otherwise the public may view them as stubborn. In a single party state, mistakes are either excused forever, or if you fall out of favor, then you have less chance to recover.

In multi-party state yes. In two-party state it's not a chance. It's inevitability.