So what exploit is this?

[Castanica]

On Siren I see a steady stream of 'naked' characters (mainly Taru) with 5/6 character names (not keymashed like RMT usually do but clearly there's a pattern to the names after you've watched them for a while), /anon and no LS, talking to the RoE NPC Isakoth, especially but not exclusively in JP prime time.

I presume they're exploiting some way to get easy sparks, perhaps by botting new character creation to complete the easy 'Tutorial' RoEs?

It's not an exploit, you can cap sparks out in a couple of hours easily if you're doing aoe.