I don't think any of the the above is strictly correct, or in perspective.

If a publishing company owns the rights to a song, its because the author has signed a publishing deal with them. Publishers are like a bank - they give you an advance against future earnings. If a songwriter has signed a publishing deal and assigned the rights in their song to a publisher, then they have already been paid their money when they signed the deal.

I don't think having a publisher means you are "screwed" and it doesn't mean you are at their mercy. If you signed a bad contract that gives all your money to someone else then I'm not very sympathetic (maybe a bit, but not that much).