Without vision, and the talent, know-how and ambition to realize it, Seibert might have become a tie-dyed-in-the-wool Dead Head selling pot brownies from the back of a psychedelicized microbus. Instead, he instigated, orchestrated, facilitated and otherwise dreamed-up the nascent visual personas of MTV and Nickelodeon, back when they were truly vanguards of the pop-cultural revolution. In the ensuing years he has exerted a significant influence on the look and content of animated cartoons, first as president of Hanna-Barbera and later as the founder of Frederator, a cartoon production company that provides programming to the Cartoon Network. If these accomplishments were not enough for one lifetime, he has recently become president of both MTV Networks Online and Nickelodeon Online, where he has had a hand in transforming the Internet by provoking, stimulating and triggering numerous creative collisions.
—Steven Heller, Essay, 365: AIGA Year in Design, 2000