Because it's made by volunteers, in their free time, who either don't have the time or skill or goal to make it competitive

Didn't stop Blender. Didn't stop Firefox. Didn't stop Linux itself.

If someone is not able or willing to learn their way around something new, that's literally their problem

I've already covered in this comment chain. Krita and Affinity Photo do things differently and nobody complains because they can see actual value in the change. Being "different" isn't the source of GIMPs reputation, being shit is.

Why would it need to be similar? If you want Photoshop, well then use Photoshop.

I moved to Affinity Photo over a year ago, despite it being different. I don't even keep a token pirated version of Photoshop around for compatibility anymore.

Sometimes doing something different might also end up being the better idea. Won't know until you tried.

I tried multiple times and it simply isn't. That's been their most common feedback for 20 years but people like you still refuse to acknowledge that people might have a point.

And yes, good software is good code. That's just a fact.

Yet somehow, no matter how good the code might be, ugly software with shit UX just never seems to gain widespread popularity. Don't worry, I'm sure it's not because "good software" is holistic, it's because the entire world is wrong about GIMP except for you.