One reason is that it's only App Store apps which are subject to individual approval by Apple. If you are an individual developer simply wanting to learn/disse

One reason is that it's only App Store apps which are subject to individual approval by Apple. If you are an individual developer simply wanting to learn/dissect/play with the inherent flexibility of the obj-c runtime, restricting access to private methods/subclasses would be incredibly counterproductive and demoralising. If you are a registered Enterprise Developer (which requires a DUNS number, a phone call with Apple Dev Relations, and a few hundred dollars) you gain additional distribution options. For example you can sign your own apps and distribute them within your organisation "over-the-air" using emailed links or a custom web portal. In general I think Apple are more concerned with the integrity of their mass-market public platform (App Store etc) -- avoiding vast numbers of App Store apps all failing at once because they make some internal framework changes -- than they are about other use cases.