Ask 99.9% of Sticher/Pocket Casts/Overcast/iTunes users what RSS is. They'll have no idea, and yet those apps rely on RSS to subscribe to podcasts.
The application can obfuscate the underlying technology. You don't need to know what RSS is to use it every day and love it, just as you don't need to know about DNS, TCP/IP, or most other internet technologies to enjoy the web.
Ok, that makes sense, although the content creators for iTunes, etc, still often have to find out what RSS is.
I'm still not sure what your point is - you said Twitter is trying to "be" RSS, but that's just the format, not the application. Twitter is not trying to aggregate content from elsewhere, either.
The application can obfuscate the underlying technology. You don't need to know what RSS is to use it every day and love it, just as you don't need to know about DNS, TCP/IP, or most other internet technologies to enjoy the web.