1. you cannot not use them - the init binary doesn't gracefully degrade in the absence of the services provided by these APIs

2. the APIs are very complex and convoluted, with deep state maintained throughout the message exchanges; so complex it's effectively impossible to redo them without basically implementing everything exactly the same way

the fact that some binaries communicate through APIs doesn't mean the system is modular, if the "modules" of the system cannot be used independently for other purposes