Why would they be? The whole point of reddit is that users can create communities with whatever moderation and content policies that suit them. People visiting the subreddit aren't prisoners, they can view another subreddit, start their own, or just abandon reddit altogether. Who cares?
As terrible and kneejerk as/r/politics may be, it doesn't need to be some neutral ground of perfect arbitration for many reasons, the least of which is that it would be asking an insane amount of work from its volunteer moderators. If it skews left who cares? There are plenty of places to discuss politics online that skew to the right.
Then advertise as such and don't pretend otherwise.
How is it misleading people? is /pol also misleading people?
every chance they get. it's more honest that way
You've explained that someone might voluntarily visit a website on the internet that contains partisan content, but you haven't explained why this is a problem. They're not trapped on reddit, they didn't pay a cover fee to enter, who cares?