What about the benefit of being able to (e.g.) update OpenSSL across the board? Imagine if each application needed a HeartBleed update because every application had their own copy of OpenSSL. How would that be preferable?

That page is disappointingly light on actual arguments. Its points can be summed up thus:

-Sun presented a paper saying it wasn't worth it

-Plan9 doesn't use dynamic linking and some of its utilities have smaller binaries than similarly named utilities on FreeBSD

-People like dynamic linking for the same reason they believe in god

-Statically linked binaries aren't as portable as one would like.

It reads like more of a rant to be honest.