People argue that you only get what you pay for, implying that free software is somehow defective. However, the same as with Blender, that couldn't be further from the truth when it comes to Image editors as well. The reality is that companies that produce paid-for programs have serious concerns about the longevity of their companies with their current business models.
Comparing their own limited teams of programmers who are doing it for the money and know in the back of their minds that they will never be recognised for their work, they are up against the rest of the world, a vast army of programmers who can discuss openly any problems they might have encountered and how best to solve them, programmers who know that their work can be inspected by anybody and therefore they should make a good job if it, programmers who are doing it for the love of it. If there is a local problem, then somebody with the required specialised, localised knowledge of that problem can solve it or explain it to people who can.
The GIMP is one of the image processing programs that I use, virtually all of the time in this case, from correcting images to making them from scratch. However, even though I use it a lot, there areas of the program that I have never used, even though there is the possibility that I might find that they could make life easier for me. What The GIMP does for me is good enough and being free, I am not paying for things I will never use.
The first job that any image editing program should be useful for is correcting images for things like density range, perspective and so on.