This is just false. I'm working with information from multiple sites, and I observe how readers pick and search for work and how I have successfully been able to market my own books. Reading serial fiction is VERY different from reading paperbacks. Heck, I would even argue that ebook reading on sites like amazon kindle is also tag driven.
Serial fiction readers don't care about genres very much---they care about sub genres, tropes, tags. You have to have a functioning tag system that compliments main genres so that niche work can be found by the readers who want them.
(Speaking of a comprehensive tagging system I've never understood tapas' tagging episode by episode. It would make sense to just file the whole book under specific tags and rank popular tags to make them easier to sort through.)
For example if a book is Fantasy and it's tagged "Enemies to Lovers" A lot of readers care more about the enemies to lovers trope than the fact that the book is Fantasy.