Instead of focusing on a technology, let's focus on a problem. This is where users and potential users of RSS have a communication problem with publishers of content.
It used to be that the masses consumed RSS feeds. So, you could have metrics on that. But, the tech giants shifted from RSS streams (which empower end users) to high control system that operate differently (social media news feeds that empower corps). This lead to a drop is RSS subscriptions.
So, why today is it useful to a publisher to have RSS on their site? This is a question that needs addressing and marketing so that people know why. The business case for them is lacking.
I want RSS. I also realize the usefulness and communication around that needs improvement.