LinkedIn has a business model conflict.
It needs to decide if it is a social network or an enterprise software company. A social network depends on open platforms and third-party developers, and an enterprise software company depends on proprietary software sold to businesses.
If LinkedIn can sort out this conflict, it can get into a different league.
If LinkedIn makes its API more open and accessible to third-party developers, it will be able to instantly charge a percentage of revenue generated by the products using its API.