Why is fast convergence desirable in networks that use dynamic routing protocols?

Routers will not allow packets to be forwarded until the network has converged.
Hosts are unable to access their gateway until the network has converged.
Routers may make incorrect forwarding decisions until the network has converged.
Routers will not allow configuration changes to be made until the network has converged.

ccna exploration 2 chapter 3 Exam Question And Answers 

Why is fast convergence desirable in networks that use dynamic routing protocols?