You could have posted that opinion as a top-level comment and/or skipped the 'living under a rock' snipe in your initial reply, given they weren't talking about

You could have posted that opinion as a top-level comment and/or skipped the 'living under a rock' snipe in your initial reply, given they weren't talking about that so they focused on the thing they -were- talking about and no rock needed to've been involved. Implying the other person is a fool for not already agreeing with you before making your actual point doesn't generally tend to strengthen said point.