This went out the window the moment that developers weren't rare anymore. Nowadays there is so many people all over the world willing and able to do the work to produce apps, apple is free to exersize their duopoly power and treat them as expandable.

I've created some iOS apps, and you can really feel this in every single interaction. From their crummy badly written out of date documentation without code samples, to the painfully slow developer portals, to the random app rejections.