Interesting. So what every president has done since time immemorial is in fact what only 2 or 3 presidents have done.
First, I am assuming you meant that statement as a question.
Second, I don't understand what you mean by 'only 2 or 3 presidents have done'.
The TEXT IN BOLD states that none of the Presidents are obligated, LEGALLY OR HISTORICALLY, to release their tax returns for the time BEFORE they were ELECTED, and none have done so.