Not only are there plenty of applications that already do this, you could also develop a firefox plugin for it. Why on Earth would you want it in the browser core?
Well, as I say in the blog post: «I’m sure there are some extensions out there doing all this already. But that’s just not good enough. It needs to be built into the browser to make it easy and visible enough.»
What do I mean not visible enough? For people to use it, they need to know about it. Most people don't even know they can use extensions (or even what a browser is), but they do know that Facebook has a chat function, because it's right there.
Remember, this is not about making life easier for geeks like us. It's about making it just as seamless to use Open web technologies/social networks for normal people as it is to use closed/private systems like Facebook.
Most people don't even know they can use extensions (or even what a browser is), but they do know that Facebook has a chat function, because it's right there.
This seems to suggest a web app or suite of web apps that "competes" with Fb, in some sense. You don't have to install (or even know the URL of) a web app! Mozilla may get there eventually, but they're not going to travel the obvious, NSA-(or plug in your favorite bad actor-)vulnerable way. I think their current work with identity on Persona could grow into that, but they're going to keep it distributed, which I appreciate.
EDIT: Now that I've RTFA, I find that you also are thinking along these lines. However, I think you've glossed over who is actually running the server. In order for Persona to function, in order for all my data to be synced across all my devices, in order for any of my friends to see any of my comments, someone has to pay an electric bill every month. If there is a vast marketplace of server-operators, they can compete on price, {NSA, advertising}-resistance, etc.
I could see Mozilla carrying the web to that paradise of individual autonomy, but I could also see Fb and Fb-alikes derailing the effort along the way. They embraced-and-extended the web once already; I can imagine them doing it again: "Sure I can chat with my friends and "like" my favorite brands through Firefox, but did you see that Facebook allows me to frobnicate my Facebook snorrzlers as well?"
I think the key thing isn't so much "built-in to Firefox" as "supported and promoted by Mozilla." Some kind of federated chat web app would be cool and, if you could use WebRTC to make the main functions of it peer-to-peer, might not require a huge amount of server infrastructure. If Mozilla could afford to offer that infrastructure to Firefox users for free, it would help with adoption.
Maybe you should re-read the article which explains with words and diagrams what "easy and visible enough" means.
The point of adding it to core is also argued in the article, which proposes an alternative to the monopoly Facebook and Google are currently obtaining.
What do I mean not visible enough? For people to use it, they need to know about it. Most people don't even know they can use extensions (or even what a browser is), but they do know that Facebook has a chat function, because it's right there.
Remember, this is not about making life easier for geeks like us. It's about making it just as seamless to use Open web technologies/social networks for normal people as it is to use closed/private systems like Facebook.