In countries like the united states, elected political leader also gets to have all o a symbolism of being the sovereign. And i think that makes it easier for them to expand their powers and make it harder for people to robustly criticise the president. In a constitutional monarchy, as well as in certain presidential systems, there is a solution to this problem. You are supposed to pay some amount of deference to the head of state, but the head of government, the prime minister, who actually decides on politics, is not above a political fray.