Not only this, but having a default and free option built in disincentivizes the kind of experimentation and creative destruction that could develop the platform. Especially if the technology itself isn’t a priority for making the browser.
This is basically how Google hobbled RSS and why it’s on life support today. Reader was great and free. It got cannibalized for their erstwhile social networking bid and the entire ecosystem nearly died when it went away because it had the market cornered.
Wait, what? You're comparing FF's bare-bones live feeds feature to Google Reader? They are night and day. Live bookamrks were meant to be a bare minimum, a starting point for users to get a feel for RSS. No one in their right mind would say they were discouraging competition and experimentation. As evidence: all the great RSS readers (NetNewsWire, Reader, Feedly, etc.) were created while live bookmarks still existed.
I do not believe that it is too expensive to Mozilla to support RSS. If you had to quantify the cost in a dollar amount, it would probably be far less than the money that they spend on single one of their promotional events.
This is basically how Google hobbled RSS and why it’s on life support today. Reader was great and free. It got cannibalized for their erstwhile social networking bid and the entire ecosystem nearly died when it went away because it had the market cornered.