You used to be able to buy physical media. And that may be what they're talking about? Hard to say. For a long time this whole write it to a USB stick and install it was newfangled and not at all common. I 100% have a version of red hat in a box that I bought off a shelf of a local Best Buy back in the 90s. Yes you could have just downloaded and installed it or created your own install media. But having your own CD burners even weren't that common at the time. I remember 1999 being when I got my first CD burner and how special that was lol. It seems almost quaint by today's standards. And downloading wasn't really an option either. 56 kilobits per second if you were lucky would have taken days and days. Now it's just minutes over most broadband.