A nice summary, Gustavo, but none of the sources you cite really consider the problem in depth. All are superficial attempts to rationalize an inherently irrational system. There are two main problems with representative democracy. The first is that the term "representative" is a misnomer. When parliaments were first attempted, each locale elected its spokesperson who would carry their wishes to the convocation. Unfortunately, when you have 300+ people all wanting different things, nothing happens. So people grouped together on the basis of similar interests (and even more similar personal ambitions) and the concept of Party emerged. What is unmentioned by all political commentators is the simple fact that at this moment the concept of representative vanished. Politicians became salespeople whose primary job was to convince the folks back home of the wisdom of the policies being presented to them. This is absolutely and radically not "representation" in any form. It is merely marketing a product designed primarily to secure votes and only occasionally, tangentially, to attempt the delivery of some public benefit.
The second obvious problem with representative democracy is its default assumption of competence. In our modern complex world it is quite apparent that very, very few voters understand anything at all. Hence we have ignorant and foolish people voting on the basis of things such as personal appeal, sound-bites, and “I’ve always voted for X so I’ll always vote for X” mentality. Perhaps 0.0001% of the electorate actually knows enough about the issues at hand to make an informed decision, and when they get this far they invariably discover there are no candidates in support of doing the rational and beneficial thing — because this wouldn’t appeal to the great mass of ignorant and foolish voters. So intelligent thoughtful people (all three of them) are disenfranchized while politicians pander to the less cognitively able because that’s where the great mass of votes are.
Dictatorship/tyranny/autocracy is by no means the only alternative to our terribly broken and unfixable mess of representative democracy; unfortunately the great mass of people are unable to see past our current system simply because it’s all they know. Just as hitherto the great mass of people were unable to see past Kings and Emperors.
Perhaps one day the few clever people will devise and implement a more adequate approach to governance. For now, we must simply accept that the Age of Populism is here and horrors must inevitably follow.