Not sure why you’re getting so many downvotes. The first two are definitely real issues with a lot of self-published work.
It is true that there are real quality issues with a lot of self-published work because you don't _need_ an editor to publish your book. Heck, you don't even need to do a self-edit pass. Write it and hit publish! But it is increasingly an expectation that you have one, because quality expectations are extremely high, especially for competitive money-making genres.
I started out self-editing and now pay for three professional edits for each release: developmental, copy, and proofread. Professional editors are not exclusive to traditional publishing houses.
My point was that, in response to the parent claiming there's nothing traditional publishers offer, these are things that traditional publishers do in fact offer an author. If you write for a traditional publisher you mostly have to just worry about writing, and, unfortunately, marketing these days.