And, even later work was done using the new film and paper hardeners which restrain swell to a different amount. And much work was done with alkaline fixers with and without hardeners.

Yes, yes, I know all of that, but the salient point remains that any method puts the same amount of chemistry (within tiny limits) into the wash water if the wash is properly done! Therefore, both methods impact on the environment in roughly the same manner. Wash aids can increase this "pollution" to some extent, or at least change it.