I believe this benefits MailChimp's business model. They charge based on how many subscribers are in your lists, so a single opt-in increases how many people si

I believe this benefits MailChimp's business model. They charge based on how many subscribers are in your lists, so a single opt-in increases how many people sign up and therefore how many people they charge for. I'll be leaving MailChimp because the cost outstrips the value as our list has grown.