What could the LLM be doing that wasn't possible inside the app? At the end of the day, the LLM is just making an API call to whatever system needed to be updated anyway, that could have just been a button in an app.
Just to be clear, the LLM assistant could be a great supplement to the app for people with disabilities or those who struggle with phone apps for whatever reason, but for most people the LLM phone call seems worse.