Smartmarket also does, in fact they're better at it than MB is. But yes, the actual bidbots require you to do any curation math yourself, and I suppose making the curation math harder might hurt their market a tiny bit. But what I see on the various support forums is that there are a ton of users who aren't that sophisticated and judge whether the bot's vote size is enough for them by completely nonsensical criteria.

I guess bot users losing money is just a second-order version of the same effect.