I recently spoke to a new writer who didn’t see the point of a critique group.
There might be people who can write outstanding fiction without feedback. Maybe experienced authors with lots of novels under their belts. Maybe someone who’s studied writing for years. Maybe an outlier — a newbie who has a gift.
But most of us live too closely with our work-in-progress to know what’s really on that page when it’s “done”. We’ve revised. Maybe the plot has changed since our original outline. Maybe we’ve changed a character’s name or backstory, or added new characters. What’s in our heads NOW isn’t necessarily what’s on that page when someone new reads it. Only a critique group or beta reader can tell you how your work comes across to a new reader.
“But why should I change my novel based on someone else’s thoughts?”
This is a great question. The answer is: You don’t have to change a single word of your novel. It’s your world, your characters, your story you’ve lived and breathed maybe for years.
But you’re going to WANT to change it.
A good critique group approaches feedback NOT with the intent of making your writing just like everyone else’s. (If this is how your group functions, then run.) Instead, their feedback should help you make your story the best it can be.
Are you doing things that detract from the clarity of your sentences? Is the plot twist you are so proud of in Chapter 20 really clear to the reader? Does your main character come off as loyal and proud or just conceited? These are the kinds of things it really helps to know before you send your story off to an agent or publisher.
I don’t change my story with every bit of criticism I receive. But well-considered comments received from someone outside my own head can help clarify my thoughts about my story, like silt settling out of water. The value of this is huge.
That said, there can be a downside to over-reliance on critique groups. I’ll link to this post by Kristen Lamb, who explains it all much better than I can.
Good luck on your writing!
Author Anne Marie Lutz 
Great reasons. I wasn’t part of a critique group for a long time and when I finally joined one, it changed everything. It helped me to look at my work as a reader would. I didn’t have to change my story or style either. Unfortunately the group fell apart and I’m back to writing without a critique group. I’m looking for a new one though. 🙂
Good luck on finding the right group!