This is a feature I do not worry about too much. There are reasons for this.
Competitors often place you on it for reasons best known to themselves.
People you leave negative or sometimes neutral feedback will place you on it.
Some place you on it for opinions you may have expressed - for example in the Forum - because they disagree with you.
There are many other petty reasons why some place you on their blacklist. It is best to move on and forget them and concentrate on your customers that do appreciate your listings and buy from you. If these offer criticism then it is these you pay attention to and remedy if you can.
My shop has been blacklisted 18 times in 10 years Reasons like our location, limited payment options etc.......There are thousands of potential buyers on Delcampe so if a very few prefer to buy elsewhere, that is fine with me. I am not too bothered about their reasons because I will never have to deal with them again..
The feature is useful for buyers as the blacklisted sellers offerings do not appear in the buyers search results.
"The feature is useful for buyers as the blacklisted sellers offerings do not appear in the buyers search results"
It is useful to me for this reason and also for those that want to exclude my listings. In fact I have pointed this out to the occasional moaner who has attacked me for not leaving feedback as soon as they paid for something and said they would not buy from me ever again because of this! Interestingly several have latterly come back asking to be removed because they wanted to buy material they could not find elsewhere from me!!
If they are blacklisted they cannot buy your items - neither can they see them in searches. But many have several ID's on Delcampe so can see your items through another ID. I always check who is buying stuff and if a blacklisted person uses another ID I block that ID as well.
Only once have I unblocked someone and this person has proved to be a regular and ongoing client so it was a wise move for me to do so in that case.