Only in the extreme short term. In the medium term, the dictator inevitably ends up severed from reality by the inability of (true) data to flow back up to the authority, which results in their decisions becoming increasingly suboptimal over time.

This is the pragmatic argument in favor of free speech, really. If for the sake of argument we ignore moral and philosophical issues, the reason why free speech is important is that in its absence information does not properly flow back up to the authorities. Free information flow does not guarantee proper functioning of the system, but impeded information flow guarantees improper functioning. If your authority dictates the use of 4-inch long bolts in a place where there's only 2 inches of clearance, and nobody in the organization has the ability to feed back to the authority that information, the only possible outcomes are bad ones. This all compounds, too; the next dictate from the authority won't be able to take into account the fact that in order to fit the 4-inch bolt in, a new hole was cut in some vital structure that shouldn't be there, and some new bad decision will be made to add load to this structure, which will cause other effects. The authority ends up living in a fantasy land.

Note how this toy example seated entirely in engineering-space doesn't have any moral or philosophical component, and yet it is already sufficient to cause a bad outcome even in pure engineering terms. Moral and philosophical issues can cause yet more problems, but they'll be arriving to a space already broken.

It also doesn't matter for my purposes why the information can't flow back up to the authority. Even a well-meaning, "enlightened" dictator can end up in this situation by sheer inability to process the incoming information. The dictator may be the nicest, most well-meaning person in human history full of compassion and love and every other virtue you care to name, and they'll still break things if they insist on authoritarianism.