That is completely and entirely contradictory to the fact that there is literally an organisation of Witch Hunters called the "Ancient Initiatic and Holy Order of the Templars of Sigmar", led by a Council of Knights and a Lord Protector on top. We've literally interacted with one of those councillors. Magnus the Pious quite literally created a bureaucracy for Witch Hunters because he was sick of them acting above the law. They very much tell other people where they go.
The witch hunters do have a bureaucracy, it's called The Holy Order of the Templars of Sigmar, and they keep track of their members, because if a witch hunter disappears, then that means something made them disappear, and a second witch hunter needs to be sent out to deal with the threat that killed the first one.
...you do know there's much more than
one group of Witch Hunters, and that order focuses almost entirely on
Sigmarite populations? There are no Sigmarites in the Moot. The only 'witch hunters' who would even
go there are secular, and
they have strict jurisdictions depending on their patrons, who
again have no ownership or business in the Moot.
So you mean that in several centuries not one witch hunter/traveler/wizard managed to escape the terrifying halfling secret police and report that the Moot is filled of solidified Dhar? Or that Clan Eshin never looted the place from top to bottom?
Let's see. Several centuries, and no witch hunter - who had no reason or authority to be there, no traveler learned enough to
know what warpstone is, because 'literal solidified dark magic' is not widely known, most know it as 'wyrdstone' which is a big part of the black market, or wizard with the right skills and Windsense? That's more than plausible.
And all of this is even begging the question that these people have a) gone inside a Halfling's house and b) been shown their collection of Weird Stuff. Collecting knick-knacks is the closest most Halflings get to Adventure, so yeah it's gonna be a
bit of a long-winded thing to sit through.
Next is 'secret police'. No, they're
Fieldwardens. Just.
Read the damn wiki. The source is 4th edition RPG on this, but I can't find the canon tier list. They're basically,
yeah secret police. Guerilla commandos who know every damn scrap of the Moot and
explicitly will fucking murder any humans who start shit. They do not protect or act in the best interest of anyone but other halflings.
Finally Eshin... yeah good luck even getting close enough to
sniff a Halfling's rock collection without being discovered. Or does Clan Eshin send Assassins to just rustle through the belongings of random people in the hopes that they have warpstone?