(This task covers actual rollback functionality, i.e. rolling back multiple consecutive edits in one step).
Rollback functionality is needed in Flow at least for some scenarios. One that I just experienced is this: I wanted to see what happens if I delete all the text of a board's header (top description). Then I wanted to restore it, but there was no rollback or undo link (see also T93492, but that's probably a different issue).
Of course, rollback is not that important for adventurers who experiment with their own talk pages, but it is probably important for reverting vandalism to the header of the Wikipedia:Village_Pump or Talk:Main_Page.