RSS is opaque as a new user. What the hell does someone who knows absolutely nothing use to subscribe to an RSS feed? You used to just use Firefox (the fact that Chrome dumps into an unformatted XML page remains the most appalling thing), but they dropped that because... because why? The fact that it isn't a built-in in browsers is easily the biggest reason for the low uptake, rather than corporate disinterest.
also, IRC had some big issues for usability that I hated even back when I first got on in like 2007 or so (nickserv/chanserv not being standard protocol level features remains obscene, and doing file transfers with xdcc was like pulling teeth), although it was pretty easy with getting what client to use (I think everyone just said use XChat, and later HexChat) discord really was too convenient vs IRC unfortunately
A lot of it really is that these protocols either aren't that good or have extremely poor support on the software side If you're pushing a protocol and don't have a decent reference implementation, no one is gonna pick it up. I saw something neat called hAtom to add syndication information to a webpage so you could subscribe to a page directly (eg, you'd be able to set up the index page with blog entries to be machine readable), but I don't know what supports it (if anything), lol.
also, IRC had some big issues for usability that I hated even back when I first got on in like 2007 or so (nickserv/chanserv not being standard protocol level features remains obscene, and doing file transfers with xdcc was like pulling teeth), although it was pretty easy with getting what client to use (I think everyone just said use XChat, and later HexChat)
discord really was too convenient vs IRC unfortunately
A lot of it really is that these protocols either aren't that good or have extremely poor support on the software side
If you're pushing a protocol and don't have a decent reference implementation, no one is gonna pick it up. I saw something neat called hAtom to add syndication information to a webpage so you could subscribe to a page directly (eg, you'd be able to set up the index page with blog entries to be machine readable), but I don't know what supports it (if anything), lol.