Just like an employer may give us a bad reference and we go out of our way to be on good terms with them so we can get a good one, why can't we do the same for them?
A potential future employer could get a “not eligible for rehire” reference if we do something that our current employer considers bad but I think we should be able to do the same for employers we've worked for. For example, after our last day, we should be able to tell other people in our field that that company will overwork you to exhaustion, management keeps pushing for updates, there's legacy code which is fucking shit and no one knows what it does, lots of pointless meetings, all that.
If they can blacklist you, you should be able to blacklist them.