Because they are primarily driven by the desire for power, the Islamists say that you need the state to enforce righteousness in order for people to be righteous. They overlook the fact that the state is overseen by people, and no matter how righteous your rules might be, if those who manage implementation and enforcement are corrupt, the state will be corrupt; even if it calls itself Islamic.
So they sort of leave this point out of the discussion, because they want us all to presume that THEY (the Islamists) are benign and righteous, so we have nothing to worry about. But imagine the audacity of that. They use as precedents, the Prophet, and the Khulafah Rashideen. The only way those are applicable precedents is if the current Islamist aspirants to power are of an equivalent level of greatness as the greatest people who ever lived.
And they say Trump is an egomaniac!