It may seem like a pointless skill but, at least in my experience, fully remote companies have to rely on it for a lot of things. I've met a lot of people who were great at what they did, but couldn't write an useful email. That's less of a big deal when you can communicate in person and smooth things over via blackboard diagrams and back-and-forth questions. But when you're an ocean apart and have only four hours of overlapping hours that's a lot harder.

FWIW, I used to be involved in hiring for remote positions at a former workplace, and we had one of these, precisely in order to see if our candidate could write an email or a wiki page explaining something. The only thing we did differently was that we used this at a slightly later step and tailored the questions to each candidate's experience, so as to avoid canned responses (not that it's hard for a good eye that has access to an Internet-connected machine to spot those).

Most of us laugh at a question like that on an application and move on. It's not worth the effort. You have no idea what candidates you never even see because of those ridiculous questions on an applications.

But more importantly for the faceless hiring entity itself, because it is very short sighted. It leaves a bad impression at the very least to some people. And more importantly, you are most probably filtering out a lot of people who want to avoid useless work (thus are more likely to optimize processes) and are too honest to simply copy and paste an answer off the internet (thus would likely be honest in their interactions as coworkers as well).