Not following one's own performance advice isn't hypocrisy. Performance might just not matter as much to Zoompf.
Yes, exactly. Maybe I should edit the article to include this, it's an important aspect. Sure, the person might be hypocritical, but this doesn't invalidate the argument.
It's like a chain smoker telling you that smoking is bad.
edit: on further examination, the examples given in the wikipedia article are really bad - because they're merely pointing out hypocrisy ("but you're -foo-") rather than claiming the argument is wrong. Person 2 in each example could quite happily be in full agreement with the argument and make the same comment.