I'm reposting this here from comments on this post:
Great comments so far. Very interesting discussion. Let's explore some other real-life situations where things needed to change but the situation didn't.
Two roads cross creating an intersection. There is a shared goal for all intersection users: allow free flow of traffic but minimize the potential for accidents. First, stop signals were whistles, but later semaphores and then finally colored lights. What hasn't changed? Why, it's the color of the lights, folks. Red means stop, weather it's on a static sign or a colored light. The mechanism has changed over the last 100 years, but the concept is the same.
Most importantly, the shared goal of traffic control hasn't changed. The world of RSS/Atom/content-syndication does not have a shared goal. Therefore, there cannot be a universally accepted method of “signalling” a way to subscribe to a content feed.
Read my traffic signalling source site: Dave's Traffic Signal Page
The last paragraph contains a lesson for us all: “However, these early electric traffic signals provided little flexibility in traffic coordination as compared to the observations of a police officer. This led to the development of traffic signal coordination. The first coordination development was the simultaneous traffic signal system which was installed in Houston, Texas in 1922. In this system, all the traffic signals on the main roadway would change to green at the same time. After that, the next coordination development was the alternate traffic signal system which was installed in the District of Columbia in 1926. The alternate system is the type of coordination system that is used today.”
Mulitple systems that do the same thing don't offer the user the flexibility to coordinate traffic (subscribed content). We need a coordinated development with a shared goal. Not a goal that everyone likes, a shared goal. Focus on the shared goal and the traffic lights will turn green.