Seems like Reddit is now in the business of banning certain domains from their website. They have banned URL shorteners, but that is for the obvious reason that url shorteners are bad so everyone is okay with that, however blocking websites that are not just redirects is another thing.
The motivation behind this is to punish websites that self promote too much but also to block plain spam. It is argued that it is difficult to fight abuse so the easy way is the censor way.
This behaviour exactly what most users who understand Internet are against, the censorship game does not work if you want to be fair. There are surely other ways of addressing the issues without resorting to such extremes, perhaps this is an experimental phase that will soon go away.. ..