The celebrity social-media comeback is a byproduct of two larger cultural trends, said Scott Lamb, BuzzFeed’s editorial director (and the 18th “most viral” person on the Internet, according to the Web site Gizmodo). One is the cultural nostalgia for which the Web, with its video clips and searchability, is such an ideal medium. The other, he said, is a softening of the “nasty and gotcha-based” tone that has long pervaded celebrity journalism. “It’s obviously really difficult for someone who’s considered B-list or washed up to break back into the popular consciousness” through television or magazines, Mr. Lamb said. “But with social media, if you’re talented and good at it, it’s more of a meritocracy. There are no gatekeepers.”