There are many times where a large form might have specific inputs that need a different label widths than what the root dataview has set. Currently, the only way to achieve this is either with nested dataviews or trying to match the exaxt widths with containers/layout grids (which is near impossible since dataviews use specific percent margins/paddings). This has been suggested before, 7 years ago, with very little traction:
https://community.mendix.com/link/spaces/studio-pro/ideas/581
There have been Marketplace modules that implement this on their custom widgets, so its clearly possible and should be implemented natively into the platform.