Why offer personalised subject lines in places where they don't work?

Why offer personalised subject lines in places where they don't work?

As the video at http://nimb.ws/TOlG3E shows, when editing the email for a subscriber to change their email address, the help under the Subject line field says "Personalize your subject line. Learn more". But if you do try and personalize the subject line, you get an error message telling you that "Special characters are not allowed".

I appreciate that this facility may not be available for these emails but then why offer the suggestion and a link to a help page that is of absolutely no use?

Yet another example of what is proving to be one of the most badly designed programs I have ever used.