As quoted from the linked post.
It looks like you’re part of one of our experiments. The logged-in mobile web experience is currently unavailable for a portion of users. To access the site you can log on via desktop, the mobile apps, or wait for the experiment to conclude.
This is separate from the API issue. This will actually BLOCK you from even viewing reddit on your phone without using the official app.
Archive.org link in case the post is removed.
The reality is that a LOT of reddit users are casuals who probably visit a couple of subs regularly using the official app or a web browser and are perfectly content with that. The issue, I think/hope, is that they aren’t the ones generating a lot of the content and discussion and they will lose interest in reddit when the big contributors have moved on.
I could be completely wrong and this may be a blip in the history of reddit, but I hope that it impacts them in a meaningful way. Reddit is 100% dependent on third parties generating content for them, so the leg they’re standing on is pretty fucking wobbly.