Fair challenge. I don't think there have been any democracies that promoted competence, so any examples I can think of will be monarchies that happened to get a good king that one time, or something to that nature. Tightly centralized government isn't dragged down to the average, so they can pull stunts like that from time to time.
Yes, there have been "expert" politicians (including monarchs) in one or two fields, but unless their govt only meddled in those areas, they were "not experts" in the rest of the things that their govts did.
Govts select for the ability to stay in power. Anything else is a coincidence. (Yes, I'm blaming "the people" here for not connecting expertise to survivability more strongly.)
And, as you point out, that's a temporary state of affairs.
BTW - Tightly centralized govts are pulled to the comptence/expertise of the center, wherever that is. It may be average, it may not be. See North Korea for an example. (And yes, you can point to Singapore.)
