“Absolutely riveting” and “compelling.” “A must-read” and “a tour de force.” Blurbs, those haiku-length endorsements on every book jacket, are a ubiquitous part of the literary scene, boldly declaring that the book you’re about to delve into is “life-changing.” Or “mesmerizing.” Or “captivating.” Or “unputdownable.”

Authors love to hate them. Debut writers struggle to gather them. Established writers struggle to fulfill requests from friends, authors who share the same publisher or agent, and promising newcomers who deserve a leg up.

The famously fractious publishing community seems to agree on this point: Blurb collection is a time-consuming, dispiriting and occasionally mortifying process, one that takes time away from the actual writing and editing of books.

But until last week, the quid pro quo cycle felt inescapable, an essential part of rolling out a book and giving it a fighting chance in a crowded marketplace.

Then, on Thursday, Sean Manning, the publisher of Simon & Schuster, announced in an essay in Publishers Weekly that authors under contract with the house’s flagship imprint would no longer be expected to solicit feedback from fellow writers.

“Trying to get blurbs is not a good use of anyone’s time,” Manning wrote. He commended “the collegiality of authors,” but pointed out that “favor trading creates an incestuous and unmeritocratic literary ecosystem that often rewards connections over talent.”

The news spread through the industry like the juiciest gossip, prompting a range of reactions.

“I do agree that the blurb ecosystem is a scourge,” the novelist Jami Attenberg wrote in an email, referring to Manning’s essay. “So many of my author friends complain about the time we spend on it!”

So far, Manning said in an interview, he has received dozens of supportive messages from agents, authors and booksellers. But questions remain about how this decision will affect the literary world.

Do blurbs really help sell books?

The truth is, no one can say for sure.

“I don’t know if blurbs have ever worked,” Manning said. “There’s no metric to tell.”

Victoria Ford, the owner of Comma, a bookstore in Minneapolis, said, “My initial reaction was that blurbs don’t matter at all.” She’d rather read a thorough summary on the back of a book, or a lively description on the flyleaf, than rely on a few beats from an established author who might have a personal relationship with the author in question.

As for her customers, Ford went on: “I have not noticed readers paying a lot of attention to blurbs, with a few exceptions. I’ve definitely sold books because a customer was browsing and saw a book Ann Patchett had blurbed. Readers trust her.”

How do writers feel about asking for them?

In one word, conflicted. Asking is awkward, but the right blurb might make a difference, signaling to readers that they should pay attention to this book, among so many others.

“Honestly, there’s never been a time in my 30-year career when getting blurbs from authors was either easy or stress-free,” Kristin Hannah, the author of “The Women,” wrote in an email. “It’s a difficult thing to ask of one’s friend and it’s even more difficult to ask for a favor from someone whose work you admire as a reader, but don’t know personally.”

In preparation for the publication “Master Slave Husband Wife,” Ilyon Woo wrote personal letters to nine writers whose work she admired, asking them to read her book and offer an endorsement. The blurbers who responded, she said, were “fairy godwriters.”

“When I was writing, I was in the deep, dark basement of my mind,” she said. “And the blurbs were the first signs of life outside the book.”

“Master Slave Husband Wife” went on to win the Pulitzer Prize for biography.

Of course there were a few requests that didn’t bear fruit; that goes with the territory. And, for the record, “blurb” moonlights as a verb, as in “to blurb or not to blurb.” It’s a complicated question for all involved.

And how do they feel about giving blurbs?

When Attenberg’s novel “The Middlesteins” came out in 2012, Jonathan Franzen praised the “artistry of her storytelling” — a cover-worthy blurb that was “helpful for the life of my book not just here but abroad, too,” Attenberg wrote.

She has tried to pay it forward over the past decade, but recently had to declare a blurb hiatus while working on a new novel.

“We all want to be helpful, but also we are busy,” she wrote. “It’s a real tussle. My long-term solution has been to cap how many books I blurb a year to a dozen.”

Hannah said that she also tries to repay kindnesses when it comes to blurbing, but that “in the past few years, it’s become difficult to keep up.”

Do readers care?

Here’s a sad truth, given how much effort goes into blurbs: They might not be that important to the average reader.

On a Sunday, 18 out of 20 readers asked in an informal survey at Indigo, a bookstore in Short Hills, N.J., had no idea what a blurb is.

When asked whether she selects books based on adulatory praise on the jacket, Jaclyn Tepedino, 29, said: “Me, personally, I do not. I’m looking at the summary.”

Sylvia Costlow, 86, said that praise from David Baldacci or Daniel Silva would catch her eye; otherwise, she forms her own opinions. Her daughter, Elaine Graef, 59, agreed: “I shop a lot online and pay attention to what other readers say about a book.”

Charles Han, 24, and Joanna Baltazar, 23, were browsing in the fantasy section when they learned the proper term for quotes on the front of books. Do they pay attention to these quotes? “No,” Baltazar said. “Never,” Han agreed.

Kevin Miller, a 67-year-old “Star Trek” fan, said he would take note only if William Shatner endorsed a book.

“I like to have the opinion of other authors,” said Sharon Smith, who is in her 70s. But, she added, reviews from fellow readers mean more: “I feel like they’re not influenced by anyone.”