[From the article]

Which rolls back your update. Which may result in an error to your users or worse, removing a bunch of data they updated and not correctly telling them that the transaction was rolled back. Especially if it was a significant amount of data entry. Or the person is the VP of Sales

This makes sense only in after triggers, really.  If the process needs to occur before the table with the trigger is updated then this won't work.  Rarely would an external process actually have to occur BEFORE the insert or update occurs.

Can an after trigger roll back data if it fails?  I thought the data was "there" by the time the trigger fires....  If it can't alter the data, is there any problem with this "Worst Practice"?