Those examples you mention exist mainly because interests with money decided it was cheaper to support communal infrastructure upon which they could build proprietary offerings. Even if they started for the joy of hacking, a lot of people were paid good money to make those projects what they are today.

That will not automatically happen for a lot of classes of software. You point out that any desktop computing task can be done with free software. So what? That doesn't even matter anymore. It's 2014 and we can't accomplish a significant amount of mobile computing tasks with free software, and those are more intimately connected to us than desktops ever were.