Yes but not all the user would have it set up. They surely consider that the majority of the users don't.

Maybe the policy about rejecting debian reports came way before they setup the repository.

Hah, wonder when that was set up (wiki suggests Jan 2016). The last time I used Wine in earnest, you had to wget a whole lot of debs and manually install them. Kudos to the project for making it a whole lot easier to stay up to date.