Yes. The thing to remember is in many cases you aren't explaining for the person you are debating with or answering a question for. You are doing it for others who may read the conversation.

I've had things brought to light in online discussion change my mind or educate me many times. When I see someone claim these conversations are useless or a waste of time, I just think they are really setting weird criteria for what constitutes a waste of time.

Sure, sometimes I ain't got no time for that, but other times I do, and I figure the same is true for many others as well.