Or perhaps because historical monarchies didn't have the same level of technology that modern liberal democracies enjoy?
At the given time, they were replaced by democracies with the same technology level they had.
The argument could be constructed that for different levels of technology, different form of government is optimal. Which sound plausible. For a very low technology level, living in a tribe was the best way of life. For higher level, it was a theocracy or monarchy. For yet higher level, it was a democracy (and this is why the old monarchies are gone). And for even higher level (today in the first world), it is monarchy again.
It's a bit suspicious that the monarchy is the optimal form of government twice, but not impossible. (Although it is better to have opinions because most evidence points towards them, not merely because they are not completely impossible.)
Or perhaps because historical monarchies didn't have the same level of technology that modern liberal democracies enjoy?
At the given time, they were replaced by democracies with the same technology level they had.
That response is nonsense, an unfair reading. Jaime already offered your hypothesis immediately preceding:
Is it because monarchies have had a tendency to turn into democracies?
He explicitly says that means something completely different.
I imagine that he means, quite correctly, that many comparisons between democracies and monarchies fai...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.