Matthew comes up with all the most thought-provoking topics.

As I read the original topic, I felt a huge amount of self-righteousness. Of course you share what you know! Then, as I read all the fascinating comments I felt that everyone said what I thought so much better than I could have said it, and reading the overwhelming response I felt less defensive. Then I began thinking about in what way I agree with Matthew's friend, and I'll lay that out last.
First, I want to say that theatre is more than a job for me. If I just wanted a way to make a living, I'd have skipped grad school and stayed at my day job, and may have been making six figures by now. Instead, I stayed with theatre because I've loved it my whole life. And the most important reason I became a stage manager instead of being an actor was that as SM, I have a more influential hand in the quality of every show I work on than in any other position. Even if I were to be a director, I'd be hamstrung by bad stage managers or poor designs, etc. As SM, I can honestly say that I've worked to make every show I'm on better than it would be without me there. So there are two derivative reasons for my participation on smnetwork.org: the first is that the best way of learning is by teaching others; the second is that through smnetwork, if my advice helps someone else, then I've done my part in making theatre better across the country. The better theatre is, the more vitally it serves the interests of our communities, in short the more demand there is for theatre, the more jobs there will be -- for everyone.
Before I say where I agree with Matthew's friend, I first have to say that I've been extremely fortunate in my career. Since my first full year with my AEA card, when I worked 27 weeks, I've worked closer to 50 weeks a year. If I was in the same situation many actors are, taking very low-paying roles in order to scrape together 20 weeks a year to keep my health insurance, it's possible that my point of view would be different than I stated above. I don't think so, but it's possible, and I'm not one to pass judgement on how other people run their business.
I want to explain where I draw the line, though. I never withhold any information about how I stage manage, for all the reasons everyone else has said, and from what I said above. However, at the root, I don't think that you get jobs because of how you stage manage. I think finding a job is a very different process from actually doing the job.
I think back to how I found my current job; I studied the websites of theatres that had larger contracts than the ones I had been working at, and noticed that a new artistic director was coming in to one of them. I made up my mind that, as a career strategy, I would be the first stage manager he worked with in this region. So I got an interview with the production manager at the time, who offered a very low-paying reading that was scheduled for just after the Director arrived in town; sort of a transition period thing. I jumped at the chance and scheduled my other jobs around that week. The week went well, and at the end of it, they offered me the mainstage show that was the new AD's first. That was the start of a very fruitful and long-standing relationship that continues to this day, six years later.
Would I have offered advice about running staged readings at the time, or beforehand? Absolutely. Would I have told other SMs why I was so interested in pursuing a low-paying reading, turning down other jobs in order to secure it? Although it never came up, honestly, I don't think I would have. And certainly not with someone as or more qualified than I to do the reading. I was focused on growing my career, thinking several jobs ahead, and feeling competitive in that respect. I don't think there's anything wrong with that, because getting the job is completely separate from doing the job.
I'd love to hear discussion about that - am I right or wrong?