As I said in the original post, it's really important that an interface like this behave predictably, and unfortunately the reality of browsers and apps interacting across modern platforms means having to do something simpler but consistent, rather than unpredictable and unreliable.
We did consider some more complex ideas, including some where maybe events would fire at different times depending on the environment, but concluded that that unpredictability would make the API harder to work with, confusing to learn, and even then not reliable. The new mobile OS behaviors for invoking the Twitter app aren't detectable from a web context (we can't know if the app is installed) so at the time you click we just don't know whether the web interface or the app interface is going to pop up. It's not as simple as desktop vs. mobile.
If mobile operating systems implement a way to send messages between apps and the web, I would personally be keen to restore the original scope of the feature: It was pretty cool. But we can't do that today, and a broken API is worse than a simple one.