That isn't how it works. Long term refusal to do it isn't evidence their engineers are incapable of it. Blacklisting sites is trivial. They've always been able to do it and they do it routinely to this day.

The reason those results remain in your searches is because sending people to those sites makes Google money, and by definition that is of greater value to Google than the quality and relevance of your search results as a non-paying user.