Why don't mobile OSes have built in help features for apps?

* Some apps do. Developers that truly care will add manuals and accessibility, regardless of whether the OS requires it. Developers that don't care or treat it like boilerplate are a problem.

* Not all developers are good writers. Not all developers budget their time or money on good writers.

* Some developers stand back and let users or communities handle support.

* Some developers use their website for support, so it's accessible no matter what you have in your hands.

* One strives to imitate the platform. But if mobile devices ship with physical help booklets, what can purely-digital apps imitate?

* Some writers make their money off of App For Dummies drivel. Should developers interfere with that market?