He seems to have a compulsion to reply to anyone that has an opinion that is even slightly different from his.
Spending hours a day on a science forum, I'm delighted when someone counters my notions. At least they've read what I think.
The sheer work in posting well written and factual opinions is, as he says, an investment in time. It makes a huge difference to the readers' ability to comprehend, and indeed enjoy, the interaction.