Love this post.
I've only made one thread on TB in my 15 years here about a problem with a bandmate (drummer, coincidentally), and I ended up quitting the band over it (it was the most successful band I've ever been in, and the first one I ever got royalty checks from, so I walked away from a lot). I didn't care who saw the post, because the issues I had with the drummer were well-known within the band, and had been discussed at length with the drummer over a long period of time.
The point of this reply is simply that although I agree it can come off as unprofessional at best and detrimental to future work at worst, sometimes folks posting these things have given plenty of thought to the consequences before finally turning to TB for support. Not all of them (us?) go about it the ideal way, but sometimes a situation degrades to the point of not really caring what the consequences might be.
Jacob