I don’t know what you mean by “kneecapped.” I’ve using Newsblur for at least a decade and it works fine.
An argument can be made that they provided an RSS reader service no one could come close to matching and basically dominated the area. Google's deep support also helped it proliferate. It is maybe underrated that RSS was likely one defense the web had against the dominance of walled gardens and social media. It allowed a lot of sites to flourish that I think would not get any traction today.
Twitter dropped RSS completely. Facebook dropped them for pages. And then other large sites (Youtube I think is one if I recall right) made it less of a public feature.
Twitter is one that's pretty annoying because there is a lot that gets posted there first before it's published or not published elsewhere at all.
In today's hyperconcentrated digital landscape about the only thing that matters for mass market relevance are the default options on client software controlled by gatekeepers.
Mozilla too has abandoned RSS, which may or may not be correlated with them being (alas) increasingly irrelevant.
Eventually lack of popular RSS clients lead to slow decline on the server side as well. A new and fancy website today using a "modern" stack more likely than not does not support RSS, its fully aligned with the "follow us on XYZ" mentality.
A friend of mine — in tech — asked me the other day where I was hearing a bunch of stuff and I said “my RSS feeds” and he laughed at me. That”s what I mean.
This is the point. Even when it existed, almost no-one knew what RSS was.
Your friend sounds rather ignorant.