Interesting perspective and i think there is some truth to it, because it's true even in companies that the bigger a company gets, even with the right systems in place, the more bureaucratic the decision making ultimately becomes. Where employees usually had direct access to executive mgt, now they have to go through layers of bureaucracy. That said, i also think at the end of the day people get complacent over time and stop holding their leaders accountable esp during the good times. That's when bad laws and regulations start getting passed, which ultimately become the proverbial boot on everyone's face.
Discussion
To continue with the simple population density idea maybe there's a ratio hidden here. Over long time frames.
(Total population size vs population density) would be a chart of sustainable accountable governance. Also maybe amplified by the speed of information.
Probably a sweet spot and a breaking point*, could make some obvious predictions with this.
Geographically large dispersed populations will be unstable and require increasing force to maintain.
Small or higher population density states will be more stable with a more accountable government. Within the carrying capacity of the land mass. ireland switzerland....
By this logic russia australia and canada will become the worst nations for it's citizens long term until they break up, even considering the population clustering.
Not sure if there would be a breaking point in the other direction? Extreme high population density. Probably not relevant yet. ( Until self sufficient dyson cylinders..)