It is the next best completely free alternative.
And if that was how people actually presented it, I wouldn't be objecting. Instead, people pretend it's as good as Photoshop and anyone who disagrees is blamed for not programming it themselves and attacked for suggesting that commercial tools are far better.
How is that an argument? How do you get the idea that GIMP is basically required to be competitive, just because it's old?
Looks like you're more interested in defending Linux software than actually seeing my point.
So why isn't it competitive? It's not because it's new and hasn't had time to mature. It's not because developers haven't put time into it (despite the ridiculous "fix it yourself" bullshit that people keep pushing). It's not because the problem it aimed to solve has been solved.
It's because the people involved with GIMP have the usual Linux community resentment about what "good software" actually is. It's fuck ugly, but they don't think that should matter, so it doesn't get addressed. It doesn't follow patterns that similar software follows, because they're used to it, so everyone else should be too.
It's the same pervasive "good software is good code and nothing else" mentality the plagues the OSS community.
But who cares? Use your shit software. Defend it to your dying breath. It's not going to fix systemic problems with the project nor fool anyone who actually tries it.