I didn't read the thread in question - from the title it just appeared that it would be all drama and little substance. That said, I am totally opposed to "support only" forums. Really, what's the point? If I come here with an issue seeking advice, it is because something I am doing is not working.
Personally, I wouldn't be posting with an issue seeking advice in a support only forum. Such forums do serve a purpose, especially when someone is making choices that are rejected by the majority of people. I had a son in public school for 13 years, ending just a few weeks ago. I never once had do defend my decision to public school him (even though it was made against my own better judgment, because I felt I had no other option). I've been homeschooling for a whopping three years, in a location that's actually very homeschooling friendly, compared to many, and have been advised to give it up, because I'm tired (I was tired when ds1 was in public school, too) and frustrated (nowhere near as frustrated as I was with the school system - and nobody suggested I pull ds1 out), and dd1 isn't quite up to grade level in reading or math (ds1 wasn't up to grade level in math at three years older...and he'd had straight As for two solid years). So, sometimes support forums serve the purpose of simply reminding us that we're not the only ones making a given choice, that said choice can work out, that such-and-such obstacle doesn't mean it's not working, etc.
How does it help to only accept input from people who've made decisions similar to mine? Aren't I more likely to get a greater variety of ideas if I am hearing from people who have made decisions different from mine?
If someone is posting to a support only forum, they're frequently not looking for a variety of ideas. They're looking for someone to tell them they're not screwing up their kids for life, because their child is a bit behind on reading, or doesn't have that many friends, or, is spending their day at a B&M "institution". I'm inclined to feel that support forums are more important for choices that are out of the ordinary, and not the typical or "done" thing. But, MDC becomes complicated that way, as the atypical decision is frequently the forum norm, so the people here making the more usual, "mainstream" choice are frequently the ones who end up feeling attacked and left out. it kind of sucks, all around, to be honest.
And, yes of course, sometimes there are those unhelpful "Public schools are evil, and that's why I homeschool" posts. They aren't helpful, but really, they are no skin off my nose. When I see a post like that, honestly, I just think that it comes from a place of ignorance about our diverse public school system in this country and I ignore it. Easy-peasy!
I get that the posts aren't helpful, but can be ignored, but I'm not sure what the diversity of the system has to do with the situation you're talking about. If Poster A is having Problem X with the public schools in her area, and Poster B says "this is why we homeschool", then presumably Poster B is talking about the same problem. It doesn't really matter if that problem doesn't apply to every public school in the country, because it does apply to both posters involved in that part of the discussion.
ETA: I have no personal opinion about whether LAS,specfically, should be support only. While I haven't quite adjusted to the idea yet, I no longer have a learner in the public school system (well, I kind of do, because of the approach to homeschooling that I chose), so the current status of this particular forum is largely irrelevant to me, personally. But, I don't think there's anything inherently wrong with having support forums in place.
Wow...I really don't have a child in public school, anymore...it's hard to believe after so long!