I can't recall many pictures that show Catherine as being intoxicated coming out of clubs, William yes, Catherine NO.
Charles, Anne and the rest of his siblings were frequently at nightclubs, barmen were much more discreet in those days and there were not the packs of photographers about then. Even if there had been, pre Diana most would have been spoken to if they had a compromising photo opportunity.
The photo's shown in that publication have, to me, been chosen to make a rather pathetic storyline.