Implying Disco Elysium is a success (or even an RPG) - it got better press for a) edgy pseudo-deep writing which spoke the to the wannabe intellectuals in gaming journalism and b) having less mechanics that get in the way.
Trying to shoehorn Disco Elysium's success by saying "The press did it! The commie propaganda worked!" is not only lazy - it's utterly stupid, because it doesn't really work like that.
Almost everybody is talking about how great (RPG) Disco Elysium is. Not just the press and award-givers, but players too (it has 94% positive reviews out of ~31 800 reviews total). It has got a plenty of language translations, a full voice acting, released or plans to release on consoles... If that is not a mark of success, then what is? Like it or not, but it is going to be a huge point of reference for many RPGs in the future. Similarly to how Planescape: Torment became a landmark for RPGs for years to come.
So why did Disco Elysium succeed where the others have failed? Obviously it did SOMETHING right...