I understand that objective in theory, but it seems impractical in the wild. Most employers won't look beyond the surface level of "This person had issues with a previous employer and feels the need to discuss them here." They won't bother to ferret out who was right, who was wrong, and whether your grievances are legitimate -- even if they are. So you're basically raising a flag, and a lot of interviers or hiring managers will treat it as such.

Think about it from their perspective. They don't know you too well. All they know, at a quick glance, is that you have had problems with a previous employer. They get your side of the story, perhaps, but how are they to know if you're telling the full story, or if you're just the kind of person who complains about things and causes morale issues? They don't have the time or the process to sort that out, so they'll default to the conservative position of assuming you are more trouble than you're worth.

I've seen this torpedo people in job interviews. I've seen it sink the candidacies of people who were otherwise in very strong contention. Is that fair? Of course not. But it's something to keep in mind.

In a perfect world, sure, this would serve as a nice filter to determine if employers are worth working for. In the world we actually live in, this filter will, more often than not, filter you out of a lot of job opportunities. Meanwhile, there are more effective and less risky filters you can apply when vetting an employer.