It then becomes a take home assignment where you get to pick the topic.

Surely you wanted to protoype some tech but didn't have the opportunity at dayjob - so make that prototype and bring it to review.

Much higher interview value than take home assignment IMO, but you need to be competent as an interviewer to enter into a discussion on something you might not understand yourself.

And it's also higher value to the person applying because they get to protoype stuff they find interesting.