Generally, this doesn’t have anything to do with the quality of a Netflix series; I think The Ranch, for instance, is just OK.
However, Shawn Levy’s comments to THR indicate that it’s not simply Netflix’s formatting that has made Stranger Things such a huge success with fans.
It’s hard to tell just how popular _Stranger Things is compared to some of the streaming service’s other originals as Netflix notoriously does not release ratings, but Shawn Levy clearly wasn’t surprised that Stranger Things was a hit, and neither are we.
In general, it can be difficult to stop watching a Netflix series once I start.