That is not my main motivation for asking this, but yes you are correct. If DDG wants to use such a list as a signal then they would have to check it a bit for

That is not my main motivation for asking this, but yes you are correct. If DDG wants to use such a list as a signal then they would have to check it a bit for potential abuse. For example to only count the excluded sites that are in active accounts used for searching, but it could indeed have other potential search improvements.