> For the actual user, the experience is inconsistent with the rest of their system.
This point is moot. If your argument is that each system has its own GUI semantics, and the developer fails the user by not developing within those semantics for that platform, then you are proposing the developer must do 1 unit of work per platform where previously it was 1 unit of work for all platforms. Therefore exactly 1 platform will be supported, and users on the unlucky ones will have exactly no experiences with this tool.
Or you can use cross-platform solutions which are themselves good tools, and disregard platform-specific semantics in favor of globally good UI/UX and let your tool stand on its own with no need for unnecessary, repetitive, error-prone platform porting.
Can you make a supporting argument for this? You state it as fact. I do not see why globally strong UI/UX should be a bad thing for users just because it disregards some standards of unknown quality on an unknown platform. Most methods of interacting with applications today are standardized and have no platform reliance; it is unclear to me why a developer whose tool delivers value in and of itself would suddenly not be delivering value to users just because their UI implementation did not perfectly match said user's preferred OS' UI standards. Actually, it's perfectly clear to me that the opposite is true.
> I do not see why globally strong UI/UX should be a bad thing for users
Except "globally strong UI/UX" is usually just design wankery that totally ignores decades of usability studies.
> just because it disregards some standards of unknown quality on an unknown platform.
Yeah, because the bleeding Windows UI guidelines that were in force for decades and known by hundreds of millions -- or are we in billions territory? Probably -- of users are "some standards of unknown quality on an unknown platform" nowadays.
Maybe you shouldn't revert to facile claims which don't even support your point, such as implying that a single good platform with good standards justifies never building anything cross-platform ever in any context?
This point is moot. If your argument is that each system has its own GUI semantics, and the developer fails the user by not developing within those semantics for that platform, then you are proposing the developer must do 1 unit of work per platform where previously it was 1 unit of work for all platforms. Therefore exactly 1 platform will be supported, and users on the unlucky ones will have exactly no experiences with this tool.