> If e-mail deliverability providers (MailChimp etc.) are involved, they usually try to either educate or fire customers who misbehave, since they don't want to get their servers blacklisted entirely.

Since "My experience with Mailchimp was decidedly not like that" seems to be attracting downvotes, I'll expand on that. Mailchimp is opt out. So when I found myself on the receiving end of some local dog botique's spam (I don't have any pets, dogs or otherwise) list that was being serviced by Mailchimp I got to go through the tedious process of opting out.

Getting off of the spam list required tracking down contact info on LinkedIn and spamming the spammers. As long as companies like Mailchimp provide opt-out instead of opt-in services, it is Mailchimp and their brethren that are the bad actors. Mailchimp and Marketo have earned a spot on my smtpd_sender_restrictions blacklist.