I guess it depends on how you define "proficiency". For me, proficiency implies a fundamental understanding of something. You're not proficient in Spanish if you have to constantly make use of Google Translate.

Could code assistants be used to help actually learn a programming language?

- Absolutely.

Will the majority of people that use an LLM to write a Swift app actually do this?

- Probably not, they'll hammer the LLM until it produces code that hobbles along and call it a day.

Also, LEARNING is aided by being more active, but relying on an LLM inherently encourages you to adopt a significantly more passive behavior (reading rather than writing).