We had that for a couple centuries where the test was birth right. Somewhere down the line, we decided to cut their heads off.
Democracy in theory gives ordinary people power to choose their country's destiny. As someone who has a loved one in sg, I think their situation is peculiar but part of it is that their "aristocracy" actually does a decent job of providing for most of the people, so they don't feel the need to revolt against the PAP. In the US, we too have an aristocracy (although people might not want to admit to it) but they have not done a good job of taking care of people and so they is currently a lot of unrest that is flaring up here and there. It has a different flavor, but there is certainly political strife. So, imo, aristocracy is not a stable system because that aristocracy, being unaccountable, can turn against the people that hold it up, and thus be vulnerable to deposition.
I don't see a massive distinction between Singaporean elite-driven one party "democracy" and American elite driven two party "democracy". Both fail in certain ways but they function up to a certain point.