Having the power to determine truth does not seem like a great way to run a society even if it gets you some easy wins on other fronts.
It might work at first and be effective for some time in the same way that a dictator can "get things done" but there is no free lunch.
Eventually you will get evil dictators, power hungry arbitrators of truth. It will bite you. It is only a question of when. It might be years or generations. The only winning move is not to play. Don't concentrate the power in the first place.
> I have no faith that there is some authoritative entity that could objectively determine what is a lie and what is the truth.
I read this as "it is impossible to determine truth". If there exists a well resourced entity who's entire purpose in life is to determine objective truth and they are unable to do so what chance do I have?
That's the problem though. Your judgement gets warped by the constant stream of lies. That's the fundamental concept behind propaganda. If you repeat a lie enough times it will be believed. Everybody thinks they're too smart to be taken in by propaganda, that's one of the reasons it works so well.