Why are people downvoting the MediaBiasFactChecker bot?

I know MediaBiasFactCheck is not a be-all-end-all to truth/bias in media, but I find it to be a useful resource.

It makes sense to downvote it in posts that have great discussion -- let the content rise up so people can have discussions with humans, sure.

But sometimes I see it getting downvoted when it's the only comment there. Which does nothing, unless a reader has rules that automatically hide downvoted comments (but a reader would be able to expand the comment anyways...so really no difference).

What's the point of downvoting? My only guess is that there's people who are salty about something it said about some source they like. Yet I don't see anyone providing an alternative to MediaBiasFactCheck...