Yes, this is really annoying, you cannot even share links to Reddit any more, because users without the proprietary app cannot view them. Don't know why they are doing it, maybe to force install the app, maybe because they want to track the users, have access to the phone and other stuff on the phone, or want to show more ads/notifications etc. (also the mobile website used to have promoted posts).
RE: Reddit is restricting anonymous access to their mobile website, forcing users to install their proprietary app. No, thanks!