I'm not blaming apps creators, cause (AFAIK) this whole "tab into window" transformation is completely custom made by browsers and also at least somewhat hacky.
Would be nice for microsoft to notice and make a 'tab' a native component, and automatically handle transformation. Especially since their own, non-browsers apps like explorer, terminal or even notepad started to implement tabs. But without that ability to rip it out, it really feels unfinished.
If it was native, we could even stack tabs from 2 different apps next to each other, as if they were websites! ...full circle back to task-bar :[