Yes and no. It is rich, but it's got nothing to do with prestige - except in that it adds to the company's prestige because of its richness.
I think publishers used the term 'back-catalogue' before film companies did. A publisher makes money both by selling newly-published books and by continuing to sell books that it has published in previous years - that is the back-catalogue. I imagine in the film world a company's back-catalogue is made up of films previously made. If you go to see Doctor Zhivago, that is part of MGM's () back-catalogue.