It’s been in their ToS since 2011 (ish) but they’ve only recently (this year, with new app review process) been enforcing it.
Even if you manage to sneak one by their reviewers, if they later learn about it (probably via a complaint, tho there are ‘rumors’ they can detect auto-fill spam patterns) then you’ll get a notice telling you to correct it or get banned, and if no corrective action then banned. hth