From the top of my head:

- captures creativity into a centralized proprietary platform on which creators have no control

- modal dialogs nagging you to create an account when you just want to read an article

- uniform, soulless, dull visual design

- heavy pages loaded with JavaScript that don't add any value for the reader

Make all the articles by default behind paywall, and even as an admin on the blog.jupyter.org I can' deactivate that, I need to ask the author that submitted it.