working pro for more than a decade now, maybe some off this was relevant very early on but it's really just all web forum gear chatter. What people miss is that a photographer's job isn't using a camera or lamenting settings, it's lighting. Done artificially or by modifying what's available, you have to master both. The camera is incidental and what he's describing his just picture taking. If you're interested in photography it's more useful to take a studio lighting course and learn about fixtures and modifiers than worrying about iso.