I didn't think this really needed explaining, but here goes anyway. As a user in a closed ecosystem like Twitter, you have no control over what content will be

I didn't think this really needed explaining, but here goes anyway. As a user in a closed ecosystem like Twitter, you have no control over what content will be served to you (the same goes for any filtering tools said ecosystem offers it's users). The state of a closed ecosystem today, does not guarantee that there won't be future state changes (and users have no control over those). With a protocol like RSS you have full control over the content being served up to you. If a source you previously agreed with and enjoyed, starts souring for you then it is as simple as unsubscribing. It will not be pushed on you. So as said before, the example doesn't really hold.