I agree with the clarification that "it's a technology that never got a share of average users aware that they were actually using it." Plenty of people subscribe to news feeds in Twitter; what do you think the backend technology is supplying them? Podcasts have also been mentioned.

People don't use RSS the same way that people don't use JSON: they don't know or care about it, but it's a key component of many of the services they use every day.