I am currently implementing this specifically for the Special:Preferences form (see T117781), but I don't think we should do this for the general case of all OOUIHTMLForms.
There aren't many forms large enough to benefit from tabbed navigation, and frankly it is somewhat difficult to implement a generic way to do this with how annoyingly flexible HTMLForm is. When doing it only for a single form like Special:Preferences, we can make it easier by not handling certain corner cases that we know can never occur.
I'm willing to reconsider this if someone provides two more examples of forms where they'd like to use this. But until that happens, I think it would be unwise to spend time on a generic solution handling those corner cases.