The only reason is people took the open source wrongly and posts things that should not be posted on such valuable and knowledgeable group. I hope you found so many restrictive things. But what we can do? They are just taking the advantage of open source for their advertisement and promotions.
and most of the senior level people always have one thing in mind, now this group is useless and people posts bad things! So, even someone like me posts some important things, it will never seen. or if seen, it might be delayed.
But it doesn't mean, we should leave hope. I agree with you, but you alone or me can not change them from posting here.
That's what open source is.