They were of no emotional significance though.
THIS
just because a character is doing something does not mean that they are significant to the emotional story of the film
You didn’t mention “the emotional story of the film”, you mentioned “making a difference” and plot-wise - they did.
Look, iS ROTJ a Eugene O’Neill play? No, it is not. Is it a fun space fantasy adventure with some silly and stupid bits? Yes.
Also, I’d say that Han and Leia DID have an emotional arc (their relationship) and Leia had a minor one with Luke too (them being sibs). Was any of this as big an emotional arc as Luke’s? No. But, then, Luke is the PROTAGONIST.