In my view, there is no sense gathering together unless we are going to be constructive
in some manner. Considering the electronic document medium which is the platform for our particular gathering, all constructive output is going to originate as typed ideas, but these can and do grow into the non-digital world offline. We may fill the spaces between idea nodes with data supporting or answering the whys and hows. These are typically reports and views from outside parties.
I do not believe any time should be lent to either the deconstructive or to the destructive participant.
We can identify the deconstructive participant as they who indicate no interest in building or exploring. Their sole interest is to engage with an idea under construction and attack it but do nothing else. This differs from pointing out a flaw, patching the flaw with a superior alternative, and in doing so taking nothing away from the whole, but rather strengthen it. The deconstructionist method is to reduce parts to nothing without filling the gaps they have gouged out of the greater structure.
A side effect of this is that no idea is carried very far and we are forced to move on to the next or while away the time until someone dares posit the beginnings of another concept. Ideas here are often whittled down as if it they were wooden planks gnawed to dust by termites.
The only local ideas that have taken root have grown because
they have been isolated from anonymous end user participants and the termites nestled in among them. Among these surviving constructions are persistence of the Nietzchean active nihilism
improvement upon nihilism and the National Day of Slayer heavy metal music holiday which has flourished enough to be publicly endorsed by the band itself.
Now while the deconstructivist is covert, and I suppose in some, but not all cases quite oblivious that they are useless, the destructive type is overt in its methods. The product and services spam that appears on occasion is an example of negative usefulness. Some other ways participants spam rather than participate are addressed here: http://www.anus.com/metal/hall/index.php/topic,10557.0.html
Why bother at all with a message board? My guess is ongoing generosity. You have a chance to add something constructive to some larger idea that may in fact manifest as something more powerful and influential than yourself such as the examples indicated above.