It may be measured, but it's not helpful.

Let's assume that Joel is neither stupid nor malicious. Therefore he is having problems that presumably others are having. In this case it is useful to actually set out the nature of Joel's error, rather than simply saying "Joel is a dolt". Non-malicious criticism can often be helpful in letting you explore why people misunderstand you.

Of course my assumptions could be wrong - he could believe that Joel is being malicious.