Worth noting that the distinction between democracy and republic that you're clearly advocating here is a usage particular to Americans. It doesn't have much currency elsewhere.
Countries like the Netherlands, Denmark etc all have safeguards the dilute the power of 50% + 1, and yet they are clearly not republics, being monarchies.
Political scientists tend to talk more of 'liberal democracy' (whether republican or monarchical) v 'electoral autocracy' etc. This depends on the classical use of the term 'liberal' of course, which is another word that Americans tend to use differently from everyone else.
> The nobility is another example of a minority with disproportionate power. It's important that they are reduced to ensure civil liberties.
Alexis de Tocqueville would disagree - he believed that intermediate institutions (churches, professions, elites, etc) blunt the power of the state before it reaches average people. A society without intermediate institutions is one where you have an all-powerful state on the one hand, and a largely un-coordinated mass of average people on the other. He thought this was the highway to democratic despotism. (Worth noticing that totalitarian governments focus a lot of their energy on destroying alternative centres of power such as these.)
