According to the same article, pushing the movie back until the late fall of that year had a ripple effect on Hollywood after Paramount and 20th Century Fox (RIP) decided to vacate the July 2, 1997, opening date to work out the kinks in post-production.
Up until the spring 1997, Titanic was scheduled to hit theaters over the July 4 weekend, but as the New York Times described it, the most expensive film ever made was pushed back as there was no way to fast-track the new and complicated computer effects that make up a large portion of the movie.