Isn't this what megacorp.io is for?
Not really because Megacorp isn't universal, it's closed. You can't add your own XMPP adress, you don't have any notification on a your desktop client or on your smartphone. You don't have all the possibilities of a client like Pidgin or Conversations and you are forced to use a browser which is not really a good choice.
A browser with extensions and lots of tabs loaded can easily take 1Go (or much more) of ram when my Gajim is limited to 60Mo.
And why bother to make on a browser that has already been done elsewhere, Time is money you know. :)
Megacorp is just another closed client who has no interest outside of Ryzom. The idea was to expand Ryzom on the net using basic possibilities of XMPP.