We do this at retriever.co for our virtual assistants, in two areas:

1. we have applicants do a data transform with an esoteric excel function that they've /almost surely/ never used, and prompt them to find videos / tutorials on how to use it if they don't know (which, we assume, they wont)

2. we have people answer fake customer support tickets that require them to do some on-the-job learning about the Internet Service Provider industry -- to a level of detail that requires that they read through and grok a page on wikipedia explaining up-time calculation.

While neither of these pieces of knowledge are necessary for their day-to-day at Retriever, they allow us to stratify candidates' ability to learn new skills and grok new information.

100% would recommend!