I don't get the use case. If I have a file to upload with 10000 emails say, then either they have opted in via an auto-responder and therefore those emails are

I don't get the use case. If I have a file to upload with 10000 emails say, then either they have opted in via an auto-responder and therefore those emails are already validated, or I have purchased a list off someone, which is potentially a bit shady but I should just get them validated again with a double opt in. Where does this service fit into that?