Early in its life, Hulu found huge success in acquiring and promoting itself as the home for old fare such as “Seinfeld” and “The Golden Girls.” But those classic libraries have become even more valuable for streaming services — Netflix paid at least $500 million to grab exclusive rights to “Seinfeld,” while soon-to-launch HBO Max will now share “Rick and Morty” with Hulu, while shows like “Brooklyn Nine-Nine” will co-exist on both Hulu and NBCU’s new Peacock service.