So the fact that a well maintained page exists for one and not the other isn’t a bias?
In other words, there’s a bias in the editors to not make it, but there’s no malicious bias that deleting an actual article would imply.
Someone first moved it to userspace, causing it to become a redirect: https://en.wikipedia.org/w/index.php?title=Talk:List_of_left...
Which then triggered it’s deletion.