The problem is that there's a very big difference between wanting a blanket ban on transition preparation and wanting the actual people involved (the trans kid, the parents, and the doctors) to do a better job of evaluating the situation and working out the best path for each case.
While your opinion may be more reasonable you should be careful to not assume they share your opinion. A lot of people don't realize that the common choice for "transition" treatments for teens does not transition them, but rather delays/suppresses puberty in such a way that they can choose which way to go at a later time. Banning this treatment forces a choice and disallows a trans person's ability to fully transition once of age.