Let’s say the ruling class of your country is full of hard working uncorruptible ascetics. They’re purely dedicated to the good of the people. Every time there’s a good idea, they implement it vigorously and without Sounds great!

In practice, this is terrible. Stalin truly believed it was necessary for the good of the Soviet people to forcibly collectivize the peasants, killing millions. Mao geuinely believed in revolution, class strugle, and remaking society, killing millions.

If your institutions is full of hard-working true believers, they’ll be willing to do horrible things for the greater good. If each institution is captured by a special interest or lobby, a would-be ideological ruler has to balance all their interests to get anything done, and this acts as a check against Good Ideas.

Now don’t get me wrong, Soviet Russia and Nazi Germany were corrupt and that didn’t save their victims. But it’s not the worst thing in the world for the rulers to be mildly corrupt and susceptible to the influence of powerful players.

Ideally you have well designed institutions, a free press, an independent judiciary, and a democratic system. In practice, institutions arise organically and evolve chaotically, so you have to be very very lucky to have those. So if you don’t what are the options?

Well a president who takes bribes and can’t get anything done without appeasing a dozen powerful groups might be so incompetent there’s a famine, but he’s also not likely to engineer famines because he thinks it’s a good idea.