I have seen multiple fan concepts of the dark ranger and some were very detailed. The banshee idea imo is cool and could be their thing. The dark rangers in wow all have a bow and a sword or dagger. A combined playstyle of ranged and couple of melee stuff with their big thing being banshee things( mind control, but instead of controlling from afar like the priest, you actually go in the target) this is just one example. It already sets the stage for something unique on my eyes.
I mean we could give this so many spins and allowing other dark ranger to be trained which is happening all the time could increase their skills. So its not farfetched to say other dr have have those skills as well.
Its not hard to explain or add. Not lore breaking etc, its more that people have a hard time imagine it. Also Sylvanas has been in the spotlight for some time now, so some like it, other are just fed up. Making it even harder for some to like or see it. Which I understand.
Shadow hunter for example are in the same place and are kinda the dark rangers of trolls. But people like them altho they lack skills etc as well. Opinions is the right word, but saying dark ranger lack stuff because they are just hunters is just wrong. They dont even use or have to use hunter abillities. Its a matter of expanding if they ever go for something like this just like everything else that did not have much to it such as Demon hunters that only realy had Illidan, like dark ranger only had sylvanas in warcraft 3.