What's funny is Gimp used to be single-window, then for some reason they redesigned to multi-window crap, and now they're back to single window (at the cost of ctrl+s -- fine, whatever). Still many UI quirks for sure. I don't know how much it matters for non-trained users though, Photoshop confuses me too on the rare occasion I get to try using it. For professional artists, they're likely using more tools than just "Photoshop for everything", so it's not like they're incapable of learning new UIs even if they suck. (Edit: And generally these days I'd rather advocate for more diversity in tooling, regardless of closed/openness, just to avoid monoliths and monoculture.)

The GIMP-over-Photoshop argument should be because it does something Photoshop doesn't (very possible with its ecosystem of plugins/filters -- for example a "smart remove" plugin was around for quite some time before Adobe made their own and spent who knows how much in marketing/demos for it) or because the artist wants to save money.

Agree that people are goal oriented. OSS that's free-as-in-beer can help drive adoption on account of being free, but ultimately the best OSS succeeds because it's better than its competition in important ways. Pure clones are risky, I'm glad Gimp doesn't try too much to be a clone.

It's not really about being incapable of learning new UIs though - I'm perfectly capable, I just don't want to. Why learn a UI that takes 3X as many steps to chop up a site design when there's one that takes X?

Sadly most artists who want to save money just pirate, which is what led to the terrible Creative Cloud situation. But that led to Affinity which seems to be a solid, buy-once (for cheap!) replacement. I agree the monolithic nature of Adobe is bad for everybody but that's not a reason to choose a subpar tool. Also people can write and sell their own plugins for Adobe products as well.

Anyway I think we're mostly on the same page.