Doesnt milk work for everyone tho ? look at brook, I believe it was mentioned before as well
Brook is some special case with his bones. And we only saw that behavior with Brook and Luffy.
Maybe it’s working for Brook cause of his DF and Luffy simply thought it works that way generally, so it worked for him too.
It also explains why his rubber doesn’t behave like rubber. Several times in the story people said Luffys Rubber doesn’t work the way it should, doesn’t behave the same way. And I think the reason is, because it behaves like luffy things it should behave.
Said otherwise:
If luffy think his arms can start to burn by pumping his blood fast enough in his arms, they can burn.
Or if luffy would honestly believe his rubber would be able to freeze something to ice, similar to Aokiji, it would.