It has implementation issues - you get to use a crusty ContentProvider or manually serialize everything into also crusty Bundle. Then you have that separate SharedPreferences thing. Or you can do it on your own, typically more cleanly, with an object database.

Instead it would be often fine if it just took a Java Serializable and ran with it, just call you back so that you can read all the state and redo whatever you need to redo.

Likewise IPC with Intents is pretty crusty as is with Binder, though bit less with the latter.