[diffeomorphism]

This does not scale well with the number of windows, e.g. going to the next pdf open might mean cycling through half your windows. Hence you get grouping to make this simpler. Whether it should be grouping by app, by virtual desktop, by time opened, "smart", manual, whatever is another discussion.

[silon42]

You cycle through most recent window that you used... there is no grouping that would get in the way.