Of course, it 's not necessary with modern films. But there are still antic films like efke or foma. They may require some.
I shoot a lot of Efke and Foma film in sizes that range from 35mm and 120 rollfilm through 8x10 sheet film. I never use hardener with these films. Use of reasonable care in handling the film is all that is required to avoid emulsion damage.
Well I did not want to avoid damage, I would like to avoid curling. I thought by hardening emulsion, it would be better. In fact no.
Sorry to say this, but of course not.
Major manufacturers learned in the past that the way film base is made, stripped, and dried has a lot of influence on the way the film dries after processing. They also learned that the additives used to the emulsion has significant influence on this as well. Not very common any more, but many old films had plain coating on the non-emulsion side to even out drying and to minimize curling. I'm afraid to say that companies that make films that have curling problems don't seem to have cought up on these things...