What does productive mean in this scenario? I know what productive means in general, and I think it means something else.?

I think it means arguments in general don't produce any positive results. By "not smart," we can conclude that the writer believes that saying something that allows or promotes any kind of negativity is a stupid thing to do or say.

The implication its that arguments are not resolutions or answers and, as a result, do not settle disputes.

The writer is trying to say that it is futile to argue, because arguments do not produce good outcomes.

"productive" means to get results. The writer is saying that arguments as they are stated on Y/A do not produce any results in terms of changing anyone's minds. They're right.