Raven Crowking- you could do that, but you'll have to do more than just reach for lower CR monsters. You'll have to carefully ration out which status effects you permit your monsters to inflict on the PCs. Something like "blind" isn't dangerous in regular 3e, because clerics can cure it at early levels. But in a low magic campaign with no PC spellcasters, its a serious, serious problem because its permanent until cured.