Guys like him are like giant stones in the river, a foot below the surface. You stand on them but don't even know the depth and extent of their importance. I've probably listened to his bass lines thousands of times but never even knew who he was until that Blues Brothers movie. As a guitarist, I knew more about Steve Cropper. As the tributes roll in, I bet a bunch of people will be very surprised at how comforting and familiar his bass lines have been over the years. It's a reality for bass players in general but he was great at what he did.
RIP to a real musician.