I wondered the same thing, but when you actually post your listing on eBay, all of those links, including Ask seller a question, are there. Hope this helps!
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .