I was wondering the same, I asked a question some days ago, while continuing my research, and found a solution that could help the community (a little bit, we are not dealing with "what's the purpose of life" questions).
I'm not going to DM everyone (community VS single), I wrote growdiaries to ask the reasons and they didn't bother to answer.
Whatever the reason is (if it is really about the contests conflicts and the self assignation of the answer, there are technical means to avoid that), they're just limiting the possibility to learn.
This site is more and more unbalanced towards the vendors goals rather than the community, or better rather than a balance between the two.