You are reasoning with your own conclusion that in the context of the question about workflow efectivenes, acceptance by users, tool usefullness it does somehow matter much or in any way – was it the library created as an afterthought or a tool created as a try to use library, or both where born at the same time. :) Who cares. It demoes everything GTK has/had, it was/is clone of photohop idea and they lost it long long ago, as it is now much less efective in it's workflows. If it was otherwise, the industry standard would be Gimp, but it is just a gimmics of it.

P.S. I'm 100% linux user, my servers linux, my desktop linux, my phone android (ok, that is halfassed linux :) ), my tools and software used, if and then possible, all are opensource and/or free. And still, after many years beeing totaly in FOSS enviroment, I just can't deny the worfly earned pedestal to Photoshop in its area of expertise. That is not to say that Gimp is somehow bad, by me it's just a remote next, and it doesn't even try to run to the same direction :) and it is his choise.