In the how this works section they detail that it comes from MDM solutions. In English this is a feature for it admins of companies who use the intune management software from Microsoft. You probably need pro or better to even use the feature.
At a quick glance, it looks to be a way of whitelisting domains at a DNS level, but with the added feature of having allowed DNS servers.
I tell non techy people to use a physical book that they can secure. People know how to do hide things or put them in a safe. Digital security is harder to understand and I would say a book in a safe place is way better than reusing passwords they find hard to remember.