… except that it does actually work. I have used it in the past, though not in recent months. You can create a staged user by messaging their email address, then immediately go and edit their preferences. You can even edit admin settings to add the staged user to discourse groups. They will then get the email notification which they can reply to as though it were a mailing list.
Another thing I have done recently on my personal forum that seems to work without issues is to invite the user as staged user, then impersonate them via the link at the bottom of the user’s admin settings. In short order the user becomes active even though they have never logged in themselves or set a password. Then you can set up their preferences.
Both of these tricks assume you have gotten permission via other channels - you don’t want to just be doing this willy nilly.