A risk lay in the fact that users with sufficient power could choose what to show and what to conceal to other stones: in The Lord of the Rings, a palantír has fallen into the Enemy’s hands, making the usefulness of all other existing stones questionable.

They aren’t just “unreliable”. They are consistently described as a tool that it is misguided to use or trust because of how suspectible it is to being manipulated and how readily it, in turn, poisons the user. If a user isn’t wary, their world-view – when informed through the palantír – will be malformed through projected half-truths and misdirections.

Even if the “concept” of a palantír is neutral (saying nothing about a magical device that enables imperceptible surveillance), it is an astounding failure of literary analysis to not get why Tolkien included them as they are – with their consistent, negative representation – in his books.