When I first started working in publishing, no one questioned the value of a publisher.
Now they do.
When I tell nonfiction writers they need to demonstrate to the agent/editor they have a big enough platform—enough visibility—to sell books without the help of a publisher, they’ll ask, “What’s the publisher for then?”
When I tell fiction writers that their work needs to be compelling, polished, and ready for publication before they query, they’ll ask, “What’s the publisher for then?”
For first-time authors who have no readership, the answer is easy. Quality considerations aside, a publisher raises your profile and makes you look bigger than you’ve ever looked before. Someone is taking a financial risk to launch your work into the world and make your name recognizable, and the risk can be taken only for a finite number of authors, so people make quite logical assumptions about quality that are in your favor.
Of course, publishers fail at launching authors every day. But authors promoting themselves tend to fail at it more dramatically. It’s not that publishing is hard. It’s the ability to spread the word about your work’s existence at the right time to the right people that’s crazy-difficult. So far, most publishers are still better at doing that.
If you’re an author who can make influencers jump when you ask, or have a siren call that lures readers to your door, then all bets are off on what the publisher is for. You’ll have to decide.