I think most people just don't really pay attention to directors. Even I only know a handful off the top of my head whose movies I'd be interested in seeing based solely on the director, and I tend to follow movie news and stuff fairly regularly. Bladerunner 2049 is also, while great, kind of a niche film and I don't think it's surprising that a lot of people don't remember hearing anything about it. I would be surprised by people not having heard of Arrival, though.