Emily Nussbaum, The New Yorker’s television critic, often tweeted whimsically about Ms. Hicks, calling her an “It Girl.” (Ms. Hicks was once the face of a “Gossip Girl”-spinoff book series called “It Girl.”) Others dismissed her as a mere factotum, especially after a report that she was once tasked during the campaign with steaming Mr. Trump’s suits, sometimes while he was wearing them. On Wednesday, after news of Ms. Hicks’s exit was announced, the New Yorker writer Jia Tolentino tweeted: “Goodbye to Hope Hicks, an object lesson in the quickest way a woman can advance under misogyny: silence, beauty, and unconditional deference to men.”

In Washington, however, Ms. Hicks’s success was viewed as a product of other qualities, including her nuanced understanding of Mr. Trump’s moods, her ability to subtly nudge him away from his coarser impulses and her skill as a liaison for some of the most prominent journalists in the country.

“When she tells you something, you know she is speaking to the president, because she is with him all the time,” said Steve Scully, the senior executive producer at C-Span and coordinator of the network’s White House coverage. “It was amazing how often he would turn to Hope and ask her questions and ask her point of view. You can really tell, seeing the two of them interact, that there’s a trust between the two of them.”

Ms. Hicks was a key point of contact for reporters, editors and executives at television networks and major newspapers. Often, she could single-handedly arrange time with the easily distracted president. At a Paley Center panel discussion on Wednesday, the NBC News anchor Lester Holt described Ms. Hicks as his first contact for coordinating his interview with Mr. Trump last May. “She was quite helpful,” Mr. Holt said.

And in an administration riven by infighting, Ms. Hicks’s privileged position with the president meant that, for journalists, she was among the few officials whose information was deemed reliable, or at least not often compromised by personal squabbles.