Some SwiftUI questions are really Swift questions - for example, this one happens to mention SwiftUI in the title because that's where the author encountered it, but it's really about the property-wrapper language feature. On the other hand, we also have a lot of questions like this one, which are about view layout problems, or like the thread you posted recently about data consistency between @Binding and @Environment property wrappers. Those threads are looking for framework support, not language support.
It's fair enough when new or inexperienced users come by and are unsure of the difference. If it is not clearly a language issue (and they can't reduce it), they should go to the ADF first.
But what we're seeing now is more and more users who are fully aware of the difference but disregard it. They either ask or answer questions even when they know this is not the appropriate place to do so. It creates a worse experience for members who don't care about SwiftUI or other Apple SDK frameworks, as now interesting topics are lost in a sea of threads asking why their views are not properly aligned and other such questions.
But the reason why these threads are considered off-topic is not just because they'd drown out every other discussion; it's because Apple has specifically asked that we not act as a support forum for their SDK frameworks.