Interesting that this idea at Co.Design would suddenly pop up in public. The first time I heard this said, it was an anonymous Sony Vaio design team member in the nineties.
Similarly, my partner tells a story about a seminar a friend sat through with a technical support service team. The first things she was told were that 1) the user is probably wrong, and 2) there’s a good chance the user may be lying.
The rationale behind number one assumes the user’s probably new to whatever system you’re supporting, and doesn’t know what they’re doing is wrong. The second takes into account that nobody likes admitting they don’t know what they’re doing—and we’ve seen it over and over ourselves. A user will simply refuse to see that their behavior is wrong, or will silently correct what they were doing without admitting it.
The point here is not to go, “Oh users! What noonces.” They’re not; we’re all users at one point or another. But the real point here is: a user, whether they’re giving feedback or asking for support, are on your turf. They can’t make secure, informed decisions because they don’t know all the angles they should be looking at.