Think of xcf as the gimp project format, similar to source code, and the exported final image as a compiled binary.
GIMP's workflow and what you describe assume you work primarily with XCF files but this is not always (or even often, for many people) the case when working with images as nothing else supports XCF files. Personally i rarely work with XCF files and only do that if i want to save images with multiple layers, otherwise i prefer to save in PNG files as those files will be editable in pretty much everything out there. For that sort of workflow GIMP's insistence on separating Save and Export is annoying, especially when i want to create a new image and GIMP complains that i didn't save it (but i did, i just saved it as a PNG file instead of the XFC GIMP wants me to use - that i have no real use for).
To be honest, I wish some other apps that have to deal with multiple formats worked this way too.
This is subjective, i do not find it better. "Period."
> doesn't let the misconceptions bite you
There are no misconceptions. I create a blank image, paint an arrow in there, want to save it as a PNG file so others can see it. GIMP complains when i try to exit because i didn't save the image. But i did, i just didn't use GIMP's proprietary file format that GIMP developers want to push.
> What you're describing is just a minor annoyance
Yes it is, i still use GIMP after all despite it. I am merely describing why i see it as an annoyance. Something being a minor annoyance doesn't mean it doesn't exist at all, after all.
Basically, you're angry because GIMP doesn't optimize its UI for MS Paint use-cases. Trading "slightly better for basic usage" with "significantly worse for any other usage" is a bad idea for a software aspiring to be a professional utility.
This is completely misrepresenting and misunderstanding what this file format even is. You might as well complain that saved games are not compatible between Age of Empires and Pokemon.
If existing formats don't support the complexity that software like GIMP requires to save a given state, then it has to fall back to a custom format. The only alternative that comes to mind is using .psd, which clearly wouldn't solve your problem since it is actually a proprietary format.
As for this "agenda" to push some proprietary format, this excerpt from Wikipedia might clear things up:
"A collaborative effort between the developers of GIMP and Krita is underway to design a raster file format called OpenRaster, modelled on the OpenDocument format, for use in both applications in a future version."[1]
Saving is by all intents and purposes understood as being able to resume work after loading the next time you use the software.
The formats available under export do not provide this guarantee, because they lose information one way or another.
Being separate features, I know this is the case without knowing what a .dds or a .tga file is, for example.
Hell, this way I can use GIMP without bothering with file endings altogether. I save the file if I want to continue work. It's automatically saved as .xcf. I export when I want to use the image. It's automatically saved as .png or whatever format I started with. No manual entry required. No understanding of file formats required. It just works, period. And it doesn't take any control from the user.