The fact that you are making the state genuinely synonymous with a specific individual? Once you do that, it's an utter nightmare to have any check against abusing modern communication methods to exercise near-limitless on-paper power through a sprawling bureaucracy, like France did.
Even during the age of absolutism, state was not "genuinely synonymous with a specific individual". And I'm talking about Austria-Hungary here, which is not so far removed from modernity that you can claim it was all an artefact of feudalism.
As for France, what you have written is... basically Revolutionary-age propaganda. Yes, Louis XIV wielded far more power than he should have. Yes, he centralized a lot. But despite all his efforts to concentrate power in his own hands, in practice he was still dependant on support of various factions such as the Church, the Parliament, the nobility and the people.
The divisions and restrictions of power absolutely must be formalized and on record to hold up with the volatility of modern population numbers and volume of goods necessary to maintain quality of life standards, or else "there's no law saying I can't X" swiftly creates a horribly socially corrosive power block.
Which again has
literally never happened in any traditional monarchy. The only countries where such stuff has happened were a) socialist popular dictatorships and b) military dictatorships. In fact, when we look at three European monarchies that disappeared at the end of the 20th century (Germany, Austria-Hungary, Russia), only for one of them - Russia - one can argue that the monarch having too much power played a role.
And by the way,
Germany was European leader in industrialization and standard of life in the 19th and early 20th centuries.
Today's equilibrium-breaking power concentrations are in intelligence agencies that structurally require secrecy to do their job, private conglomerates accruing more wealth than many nations, and academic circles being infested with leftover Soviet shenanigans, but it's been the monarchs finding they can in fact accrue massive control over their lands or following private ties right down the drain in multiple periods. Most poignantly the "Enlightened Despot" absolute monarchs informed by the Enlightenment and dragging the whole of Europe into a culture-shattering bloodbath spawned by a fool thing in the Balkans.
Today's equilibrium-breaking power concentrations are located in a) the banks and b) the media, none of which give any shit about the so-called "democracy"/"republic"/call-it-whatever-you-want, and which have successfully subverted literally all "democratic" governments to the point that said governments are knowingly and directly acting against the interests of their own people in the way that no monarch ever did.
Also, if you really think it was
monarchs who caused the First World War, sorry, but you
really need to brush up on your history... even the most superficial reading of actual events is enough to debunk
that particular lie. If anything, monarchs themselves were the people who were
most active in trying to prevent the war - literally all monarchs had engaged in very active efforts to maintain peace, both through official diplomatic channels and through private correspondence. None of them wanted war.
Problem was precisely in the fact that they couldn't go against their governments nor the public opinion. And it was public opinion that was decisive. The only thing you can say against monarchy is that having a figure as beloved as Franz Ferdinand was pushed the public to call for rather ill-conceived actions; but United States are not monarchy and they did the
exact same thing in the aftermath of 9/11, invading not one but two countries on mere suspicion of having ties with the terrorists.
Furthermore, every single word out of your mouth about "legacy" can be readily demonstrated to be shit with the Habsburgs, most Egyptian dynasties, Middle Eastern consanguineous marriages, and the prevalence of hemophilia. Every single time it becomes a major consideration for power, the inbreeding coefficient starts climbing quite dramatically. And elective monarchies are largely interchangeable with the modern concept of elected heads of state, differing solely by those casting votes which... Is usually the inbreeding-bait hereditary aristocracy.
Yeah, no. There is literally no reason why monarch's spouse has to be from a royal family. In fact, for most of the Middle Ages that was not the case - it was only when royal families became obsessed with gaining land through marriage
and consolidation meant that the number of states in Europe had dropped
significantly, that inbreeding became an issue. And even then it wasn't so bad that it significantly impacted their ability to rule (except perhaps for some of the Habsburgs).
For Egyptian dynasties, their inbreeding was a product of religion, not the fact they had monarchy. As for Middle East, they have inbreeding there, monarchy or no monarchy. And breeding with goats and other fun stuff. All of which, by the way, was
much less of an issue while they were under monarchies than later when they became ruled by dictators, and even said dictators were arguably a better choice than later democratic governments.
And no, "elective monarchies" are
not interchangeable with the elected heads of state because a) you do not expect to elect
another monarch until one in power has died (and usually not at all if said monarch has any kids at all) and b) monarch has moral and traditional authority that an elected head lacks.
So in conclusion: please learn about some historical monarchies, rather than just reading what is essentially post-French-Revolution anti-monarchist propaganda.