This is a point we disagree on because my understanding of deemed consent is exactly what you have outlined and yes you do get people door knocking and mail via snail mail from people trying to sell you things.
The email I sent 1 to each listing owner was not selling Viagra it was advising them they are listed on the website, information related directly to their business.
The reason I ask to unsubscribe is to remove the information placed on the site as well as your email address, if you do not wish to be on the site or are not happy with the information published.
This is probably not a requirement however as a small business owner I would prefer to know what information is published online about my business and have a say in this information, on several occasions I have found information (which I have not submitted) on directory sites about businesses I operate and then taken (in some cases) weeks to sort out or have removed.
I thought it was simply polite to let businesses know they were listed and also advise them how to be unlisted if required. If by doing so I have offended anyone I apologies.