I'm not an economist, but I really can't see how information asymmetry can be considered a _good_ thing.
If the maker of the hypothetical voodoo pebbles makes a claim that his pebbles make your system _sound_ better, then he should be amenable to proper testing of this claim.
If he is not, or such testing proves that people actually can't hear any difference (and, for the sake of argument, they don't do anything measurable, either), then I don't see why you would have a problem with him being prevented from making such false claims.
If he simply refuses to submit to such a test, and a reviewer calls him, what is your problem, exactly?
Not to be inflammatory, but this argument seems to me to lead to the conclusion that, eg, the marketing of quack treatments of cancer is ok, as well, and that any attempt to destroy the market for them is bad on ideological grounds.
I think the main point the objectivists are making is that some of these manufacturers are making clearly dishonest claims, and that technically unsavvy people are not being given the information they could use to evaluate this.
If better information kills the market in voodoo pebbles, why is this bad? If they can sell the pebbles purely on the basis of prestige or exclusivity or whatever, fine.
But that often does not seem to be the case. Again, if they are making essentially fraudulent claims, I cannot see the harm in this being pointed out. I think the destruction of the Laetrile market was a good thing....