I mean, requiring FaceID is a horrible idea, but there maybe might be a better alternative (I'm talking about the general idea of a "proof of humanity" online, not specifically using this solution).
The fact of the matter is that bots are a massive issue online. When russia got sanctioned and cut off from the western Internet, r/Conservative went radio silent for a couple of days - until they figured out how to VPN through the Netherlands. There are whole communities where bots discuss bot-posted content. And I have no doubt in my mind that it will also happen on Lemmy as soon as there's even a hint of profit* to be found.
* "profit" not as in "monetary gain", but as "any kind of gain, be it money, influence, propaganda, chaos", etc., etc.