Sylvanas never stopped being a Dark Ranger, did she? So yes, Dark Rangers have relevance to the Shadowlands story literally because Sylvanas is a Dark Ranger.
Sylvanas displayed her Dark Ranger abilities in full in combat against Bolvar, which allowed her to obtain and shatter the Helm of Domination. She then again has her Dark Ranger abilities displayed in full in her raid fight. So yes, I would say the story would change if she were not a Dark Ranger. If she were not a Dark Ranger, then her methods of obtaining the Helm of Domination and her Raid fights and the weapons she drops would be quite different in the story.
Like, Cataclysm wasn't focused on Shamans, but it would be massively different if Thrall lost his Shaman powers like he has now.
You said her being a dark ranger is completely immaterial to the story being toldTeriz literally said that because Sylvanas was a focus of Shadowlands' story, that means dark rangers are the focus. You are also claiming that, mind you.
It is not immaterial, because she literally uses her Dark Ranger skills to obtain the Helm of Domination and shatter it. All the techniques she uses to defeat Bolvar comes from her being a Dark Ranger.
Again, just because you didn't agree with the opinion does not mean it was a mistake. And trying to claim this as a factual matter? You're either intentionally lying, or being ignorant. I honestly can't tell which, but that's up to you to decide.Are you going to honestly tell me that he did not mean that those two were the only options?
At no point have I ever seen Teriz proclaiming his opinion that those two were the only options as being facts. I want to point out that this is something you are claiming, with absolutely no way to actually prove it is a indeed a fact.