B&N makes way more moderation decisions than an ISP, they promote books, they recommend books, they lay out a store so you can browse the different books on off

B&N makes way more moderation decisions than an ISP, they promote books, they recommend books, they lay out a store so you can browse the different books on offer. They aren't a dumb pipe like a good ISP. Specialty bookstores are even less like an ISP, they might restrict themselves to one or a handful of genres. Leftist bookstores have an ideological filter. And so on. None of them are like ISPs at all. It would be weird to make Medium treated like a publisher for hosting a defamatory blog post while a bookstore selling a bound copy of the same content would not be. That's why section 230 is a thing!