At this point, nothing mattered more to Berry Gordy than the career of Diane Ross. So this was a showcase for her. Ironically, though, the Temptations were hotter in terms of record sales. They would go on to have several historic number one hits that year and in '69, '70 and '71. At this point the act previously known as the Supremes were done being a hit group.
With the expulsion of group founder Florence Ballard, the year before and the minimizing of the role of Mary Wilson to deep background vocals, the group had lost it's soul. Gordy needed a platform to keep his lovers' career from tanking; So he used prime time TV with this show and one the next year, called "On Broadway" to give the illusion to general audiences that everything was still good.