I have to disagree with you about editing being unnecessary. Of course, I'm a book editor, so that's my bread and butter. However, so many people think editing is all about catching typos, and it's not nearly that black and white. Editing is not spell check. Yes, we try to catch all the typos, but depending on the type of editor, we may be looking for overall plot and structure, sentence styles, repetitive phrases, clichés, character development, and much more.
And most professional editors despise Grammarly because it will provide just about as many wrong suggestions as it does helpful ones. Someone who may not know any better could ruin an otherwise decent book by following the advice.
That said, I do think a good writer can do a decent job of self-editing to a certain point, and I know some writers who need very little from an outside source. There are also great books to help with self-editing, like Richard Bradburn's Self-editing for Self-publishers. But everyone needs at least a couple extra sets of eyeballs on their work—we see what we meant to write, which isn't always what makes it to the page. Bradburn's book is a fine example: he's a book editor, and he had at least six editors in his professional circles looking over his book from various angles before publishing.
One of the commenters here claims that editors "half-scan over much of the text" and don't care as much as the authors do about their books. Hard disagree there. An average 50K book might take me 25 to 40 hours to copyedit, depending on what the book needs, the quality of writing, and whether there are fundamental issues that should have been taken care of by a developmental editor first. And I am every bit as invested as the author, because their final product reflects on the quality of my work too, and I want to keep my reputation intact. Also, I'm really proud of the authors I work with and want them to succeed!
I always wonder how people come up with wild numbers like $5000 for a copyedit on an average-length book. Perhaps they're going through a middleman like Reedsy. But there's an editor for every budget, and most of those same editors can be found on their own websites with pricing that doesn't have to include a percentage paid to anyone else.
The other four points you've made are spot-on, though. I work mostly with self-publishers, and they put out some amazing work. All of them chose to self-publish not because of getting rejected by publishers, but because they wanted full control over their own product. At least three of the authors I work with make enough that it's their sole income.
My apologies for the super-long comment, but (clearly) some of the editing comments struck a nerve. There's just so much misinformation out there. If nothing else, hire a final proofreader who's not someone's schoolteacher aunt or a neighbor, but who actually knows the style guides used in the US and UK and can make sure your books are following the industry standards. You want them to stand out for good reasons.
