Those fields are excluded because authors in those fields are quick to use LaTeX which encourages good editing, or at least makes papers look professional, not

Those fields are excluded because authors in those fields are quick to use LaTeX which encourages good editing, or at least makes papers look professional, not because they are better at copyediting or at writing English. Copyediting is still badly needed, but that's typically foisted upon a grad student; the journals don't contribute much as far as I can tell.