Well, here's one great example of why our country's founders balanced power between several, theoretically equal entities. Because when one guy runs the whole shebang and can, depending on his mood, either bless you with a palace stocked with slaves, or have you impaled on a stick, you've got problems.
Now, if you've ever been to Russia, and it just plain drives you nuts that they overtly charge foreigners more and Russians less for train tickets, theater tickets, tickets to the great palaces... or if you wonder why, when you wear your all-welcoming American smile out in public and people stare at you as if you're scaring them, you have a taste of that special Russian psychosis that is the product of 300 years of Romanov, followed by 80 years of Soviet rule. We don't know that kind of mental cruelty here because the guy at the top of our political heap gets 4 years (8 years maximum) to make his own special mess of things, before he's back in the private sector with a book deal, a pension, a list of lucrative speaking engagements, and a library to play around with. Not so in Russia. Not now; probably not ever.
Russia had what many consider her golden age in the 18th century, starting of with Peter the Great (Peter I), who modernized the country, brought it European culture and manners, but also was ruthless and paranoid. (Ruthless and Paranoid are constant companions to dynastic rulers, our country's founders well knew.) Then, following a string of mostly undistinguished rulers, including an actual baby, with various intrigues along the way and we get to Catherine II (the Great) and her reign of 34 years. Catherine had a firm grip on the country, enlarged its territory and its cultural treasure, and did everything she wanted. She thought her own son, Paul, didn't have the right stuff, so she nurtured her grandson Alexander in the ways of leadership, and made it clear to her functionaries that she would prefer that Alexander run the country, rather than her son Paul. After she was gone, of course.
And Paul made it easy by being a ridiculously bad, crazy, lunatic. He worried more about marching his soldiers around in perfect formation than in the balance of trade or the myriad internal affairs that make an empire hum properly. Paul turned into a religious fruit loop and terrorized all around him, including random citizens who were simply unlucky to be on the street when he occupied it. Not having our wonderful instrument of a "term" of service, it was necessary to remove Paul by force. He resisted abdicating, so they had to kill him. Alexander got over the regicide of his father... but every now and then it haunted him.
Author Troyat is good at is giving a novelist's touch to this history and enlivening it. The first dozen years of Alexander's reign needs very little polish to make it interesting. He began full of freshman energy, holding out the possibility of reforming the government into something more like a constitutional monarchy, and even hinting at easing up on the Russian peculiar institution - serfdom.
Then Napoleon enters into Russian affairs, first as someone Alexander admires, later as an enemy of all Europe and Russia. Alexander's army (and Russia's winter) collaborate in Napoleon's retreat and eventual abdication as Emperor of France. Then, there's that inevitable "now what?" moment, whereupon Russia became responsible for "fixing" France (sort of like the United States is now responsible for "fixing" Iraq and Afghanistan). The most creative solution seemed to be to restore the Bourbon monarchy by hauling Louis XVIII's fat ass out of exile. And of course, Louis' initial modesty fully flares into the sort of corruption and decrepitude that led to the Bourbon monarchy's earlier downfall...
It didn't take long for the luster of defeating Napoleon to fade and Russia's refocused attention on its real problems to displace Alexander from his pedestal. Alexander's essential incompetence eventually leads to the kind of talk among many that helped bring his father's rule to an end. But nothing came of it. His succession is neither simple nor smooth; when Alexander dies (in a remote area of Russia, far from St. Petersburg) there are dueling factions who wish to support one brother, Constantine, who renounces the throne, and another, Nicholas, who gains power and vanquishes some (and executes others) of those who had supported Constantine in the hope that his regime would abolish serfdom (the "Decemberists").
After Alexander I, Russia had two more Alexanders and two Nicholases. We all know how that second Nicholas ended. But that's a different and sadder story.