Trendy Faerie Charm Start on Supports?

I've seen several supports lately start faerie charm (or two of them) and no gold item. Why is it so popular? Every time I've seen it it's been absolute trash, especially because the players that took it weren't even harassing all that much (which I assume is the point- More mana, more spells, more harass?)

It really cracks me up, though, because then I just "outfarm" them with my spellthief and have more ap anyway so my poke hurts more.