Comment by ankit219

modular does not mean in terms of how the library is architected, but in terms of how many vendors/customers it needs to support. Airpods' hardware is built and then kernels are written in a way to compliment each other and get the most out of the system. With another set of headphones with a different chip, there is a very good chance that code written today would not be optimal because other builders could manufacture different things based on the same spec. You cannot bring everything to software, nor can you have hardware doing everything. Tradeoffs would be needed.

The issue comes in second order effects. If third party headphones are given access and then the experience is not as good, they complain that Apple hasnt open up the spec enough, and it just results in Apple being forced to be modular in their approach.