I believe the f64 folks wanted to promote photography as an end unto itself, not just a technology for pictorialsim...which is, I believe the basis for their disdain for pictorialists and in particular Mortensen, who's profile and writing made him a target. There's an irony in how, as photography became more documentary...or more conceptual...or more of a consumer technology, it effectively (to an extent) made the likes of Adams a pictorialist himself...dismissed by many as a technician and a maker of pretty pictures.