In what follows I do not mean digital photo editing with photoshop etc. I mean picking out the good ones.
Most writers of any understanding know perfectly well that they cannot edit their own work with any effectiveness. There are editors out there that do this for you. There's some notion of objectivity, some notion of distance from the work, that seems to be mostly required to make most writing good, and any writing truly excellent.
When you make a photograph, you know what you intended. You know what the important things are, you know what doesn't matter. When you look at a picture you made, generally speaking, all that stuff comes back to you and you see the picture you meant to take. Sure, there are methods for getting some distance. Put the picture away for so and so many days, weeks, years, and come back to it. Those help, but unless you have a very poor memory or a very large number of pictures, you'll never quite shake the picture you meant to take, and that's what you'll tend to see instead of the picture you actually took.
Why do photographers think they can edit themselves? We all do. Many professionals are even required to. Wedding photographers shoot, edit, and produce the final set of pictures, all in one for the most part. Arguably things like weddings are easier to edit, since there's the required shots and you simply pick the from the instances of the required shots those that have the fewest technical problems, and best embody that well known picture. Arguably, though, that's a problem. Probably the results would be better if someone else did the editing.
I have argued that some photographers may be almost entirely creations of that editing process (Winogrand, Maier). We don't know, but we know that they certainly did not edit themselves, and that their work at the very least benefitted immensely from that third-party editing process.
This is an area in which critique can really help. The simple information that some picture simply isn't very good might be the most valuable thing a photographer can look for from others. When you get that, respect it. It might not be true, the viewer might be missing it, or not "getting it" or something. If you've chosen someone sensible, someone you trust, to look at your picture, you should not dismiss their view lightly.
Your editor is your friend, your editor is how you get from good to great.