I've read a number of wildly successful indie ebooks that I found disappointing. Sales figures say I'm wrong.
If a book goes through the process of traditional publishing, you hope that having an experienced eye look at the project will give the writer another point of view. Sometimes you really are just too close to see issues. Sometimes you can defend your choices too vehemently. Sometimes you just need a dialogue instead of a monologue. Feedback. But it's not enough to be judged by your friends and peers, you need someone who knows more than you do.
That's what traditional publishing is supposed to offer. And this is what indie publishing can't offer. It's indie.
You can try to hire an editor and hope they know more than you do.
Or you just publish and let the reader decide. If the sales are strong, you done good. If not, you failed.
You can stop there if you are satisfied with mass opinion. Is there a reason to try for anything greater than great sales? What is quality? Is quality measured in numbers or is it more nebulous than that?
Should we dig deeper or try harder?
Are these just foolish questions?