Users are not designers.

If your users have many questions, it's a failure of your primary site design. It becomes not so much customer support, as much as customer complaints.

Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.

Users are not designers.

Popularity is the product of two factors: (a) how compelling material you offer, and (b) how easy it is to access it. Host free pirated movies and users will flock to the site, even if it's difficult to use.

On average, when you ask someone to perform a task on a site, they cannot do it. It's not their fault; it's the designer's fault.

What we learned is money doesn't grow on trees.