I run one of the more popular readers and I have to ask why wasn't NewsBlur included in your list. It's the oldest on that list for one. It's also got its own native client on all of the platforms. Plus, I'm a HNer and NewsBlur launched on HN as well.
As somebody who has been introducing people, in person, to the concept of RSS for exactly a decade now, I'll mention that for those who really haven't heard of it, which is 10% of folks in tech and 90% of everybody else, my strategy has been to compare it to an inbox for websites with filtering and sharing. Really hits home on the idea that every story shows up unlike the dominant competitor to RSS which is FB/twitter.
95% of the people who leave RSS, and I ask everybody who cancels why they're canceling, leave it because they get their news from social media. Social filtering provides a higher signal than the manual process. I don't blame them.
Personally I built in that serendipity into my reader because I think it belongs in a news reader, but as its own feed among many.