From your documentation:
>We recommend that an unsubscribe link be added to all mass emails containing promotional or marketing content, but the decision is up to you.
An unsubscribe link is a requirement of the CAN-SPAM Act and the GDPR. Your own docs effectively say "We advise you not to use our product to break federal and EU law, but the decision is up to you". I can't speak for anyone else, but that doesn't really accord with my sense of ethics.