It's serious, the person you replied to is talking about how to revive a dying _thing_. Whether you want to call it a spec or a brand or a product does not really matter in this context, RSS has elements of all three. Their point is that trying to get people to change their minds on RSS is going to result in wasted effort, and that if you want RSS to live you need to market the hell out of a functionally equivalent replacement to the spec that appeals in some way to the relevant decision makers.
All things you are trying to get others to use have a brand, whether implicit or not. Heck, it's usually even valued separately from the technology (good will, etc).
RSS, the spec may be fine. I've implemented RSS readers, heck, i use newsblur every day still.
RSS, the brand, is a goner.
The OP (and twitter post) is complaining that others consider the brand dead, and are arguing that the use case it covers are unmet by other things, and that the spec is still good stuff. Those are all very orthogonal things.
It's great that the spec is still the right thing! But the brand is dead, so you won't get anywhere without fixing that.
If we use the term brand to mean, "reputation," then yes, adoption is a function of reputation. Reputation can be justly granted (due to things like the functional value it provided) but it also can be disparaged regardless of the merit of the argument.
If enough people think that RSS sucks, is too old, died with GReader, has no user-base, or whatever other story, why would they invest their time and effort in supporting it? If the problem isn't technical, then it might need some kind of marketing solution to get over the historical baggage in the zeitgeist.
Okay, I get that "brand" means "reputation", but why should a highly useful technology be worried about it's "brand". Is the "car" brand out of vogue? What about HTML? I mean, that stuff was used in crickety old sites from the 90s! Should we throw away our hammers, because screws are all the rage?
This whole notion of RSS' "brand" being the problem just reeks of a used car salesman trying to convince me that spare tires are for chumps.
Being highly useful is simply not enough. It never has been. OS/2 did not win.
The world is littered with highly useful technologies that nobody adopts, or eventually die to less useful, arguably objectively worse technologies.
Adoption and software life cycles are not a techo-meritocracy.
In short - you are completely and totally ignoring the social aspects of software adoption and use. But they are, in fact, often the most important part. I don't actually particularly like this any more than any other software engineer - it often feels wrong. That does not (and will not) make it any less of a reality.
(as an aside, yes, in fact, as joist hangers and ties and such became more and more required due to code or construction method, structural screws became all the rage - nailing joist hangers/etc with regular framing nail guns was hard and dangerous, but structural screws just require an impact driver or a screw gun to do safely. Now they actually have specialized metal connector nailers, so structural screws are getting ignored again outside of decks)
This is the realm of perception not reality. The perception is that RSS has been deprecated like java applets or activeX controls. I'm not convinced we need to "rebrand RSS," but we do need to have some activity demonstrating its modern relevance.
Usefulness isn't a high enough bar. When choosing a technology, I might also want an active community, for support, for ecosystem tooling and integration, and more.