I’ve seen this said before. Before I answer I wanna say to people that think it has to be an original vampire, it doesn’t as Freya was gonna turn herself to Be a vessel for the hollow.

And to answer, it’s basically plot really. But I guess they say the Mikaelson were trying to change and not ruin innocents lives and that they were having to think on their toes

But even if they was the case about innocents, They could’ve put one in aurora, Kol was gone with davina so him being a vessel I don’t think much of a problem, same with Rebekah being with Marcel however since I reckon Rebekah would’ve been more Inclined to visit hope and others than kol I reckon they could’ve used marcel instead. So that’s 3 done and so that would leave the choice of either to allow klaus to be with hope or to allow Elijah to be with hayiey which isn’t even a question that Elijah would make the sacrifice.

I think even the scenario I gave would been better as at least klaus is in the picture and can be hopes father and Rebekah is there also and at least Rebekah can visit Elijah and kol

But yh it was just plot and at that point in time writers just wanted to end the show by any means necessary