Or, Lord Acton again
"I cannot accept your canon that we are to judge Pope and King unlike other men with a favourable presumption that they did no wrong. If there is any presumption, it is the other way, against the holders of power, increasing as the power increases. Historic responsibility has to make up for the want of legal responsibility. All power tends to corrupt and absolute power corrupts absolutely. Great men are almost always bad men, even when they exercise influence and not authority: still more when you superadd the tendency or certainty of corruption by full authority. There is no worse heresy than that the office sanctifies the holder of it."
Any person who achieves power, sincerely believing in the importance of accountability, will find that the importance of accountability declines rapidly to zero as a function of time.
At its natural limit, desire for power excludes desire for accountability.
The healthy consequence of absolute lack of accountability is absolute lack of power.