I think the article's lack of attention to both these interfaces being conversational as well as auto-translating unfortunate, as I think both of these things would suggest on average they may be substantially more accessible than alternative interfaces for the users they're calling out.

Admittedly without numbers to bear this out, I've been consistently impressed by the quality of modern text-to-speech audio transcription, and LLMs are, when provided with written dialogue, fairly skilled at replying with usable-to-spectacular results. This suggests a serious potential for improved usability for these low literacy users by expressing their queries as a verbal and untyped stream-of-consciousness by using transcription, while still giving them back well-formed results in response.

Additionally, to the extent that this is a problem for non-native speakers separate from native speakers specifically, one of the benefits of LLMs is that they often are capable of generating well-formed inputs in multiple languages trained in their corpus - this suggests that even on an interface designed without localization in mind, Prompt-driven UX can potentially give you user-language localization essentially for free.

Given these two points, I don't like the assertion that these kinds of interfaces a priori hurt usability, because they assume a framework of interaction that first doesn't have to be used, and second ignores the users whose usability would potentially be greatly empowered by these kinds of interfaces.