Scott is desperate for people to accept his view. He verbally battered Ford into submission, and admitted as much in an interview 
It's basically all coming from Scott. He has the idea that Deckard is a replicant, and for some reason he's really hung up on people embracing his "vision" for that character.
The screen writer said there is no answer. Ford says he's human. From what I've read he's human in Dick's book. The story has more emotional weight if he's human, and less contradictions.
Everything about him being a replicant is Scott's vision/interpretation. As the audience you have a choice.
1. Do something better with your time than worry about this stupid issue
2. Accept that Scott is just the director and not the sole authority.
3. Make your own choice on personal preference.
There is no "truth". It's a work of fiction. The answer can be whatever you want it to be.

It's basically all coming from Scott. He has the idea that Deckard is a replicant, and for some reason he's really hung up on people embracing his "vision" for that character.
The screen writer said there is no answer. Ford says he's human. From what I've read he's human in Dick's book. The story has more emotional weight if he's human, and less contradictions.
Everything about him being a replicant is Scott's vision/interpretation. As the audience you have a choice.
1. Do something better with your time than worry about this stupid issue

2. Accept that Scott is just the director and not the sole authority.
3. Make your own choice on personal preference.
There is no "truth". It's a work of fiction. The answer can be whatever you want it to be.