The primary reason is of course encapsulation. Many things you don't want to leave publically accessible. For instance if you're creating a thread safe api, you

The primary reason is of course encapsulation. Many things you don't want to leave publically accessible. For instance if you're creating a thread safe api, you need to be mindful of references/mutexes/locks which can easily be enforced with wrappers. If you expose the underlying objects directly you could easily dead lock, corrupt memory, create race conditions, etc. It also greatly simplifies testing and guarantees/provability since you can guard against access patterns or certain inputs or states. Personally, I have run into enough horror caused by mutating a global state that I write code which is quite strict about what it exposes. If you're a python dev, I'd suggest reading this (posted on hn recently but I can't find the hn link currently): https://instagram-engineering.com/python-at-scale-strict-modules-c0bb9245c834 https://instagram-engineering.com/python-at-scale-strict-mod...