I have googled this and even got to the second page, and there does not seem to be any kind of consensus.
As far as I can tell, it's a bad idea because it creates code you don't see and accepts inputs that you wouldn't want. And yet, many people seem to like them more than, say, const unions due to being easier to refactor in bulk.
So what gives? Is this a case of IT people having very strong opinions on stuff that doesn't matter? Or is there a technical reason for or against it?
Basically, you can use them if you want to, but every single case where you would use them would be better served with a union type.