the optimization you describe here is not valuable enough to offset the value provided by statically linked applications
the computational model of a fleet of long-lived servers, which receive host/OS updates at one cadence, and serve applications that are deployed at a different cadence, is at this point a niche use case, basically anachronistic, and going away
applications are the things that matter, they provide the value, the OS and even shared libraries are really optimizations, details, that don't really make sense any more
the unit of maintenance is not a host, or a specific library, it's an application
vulnerabilities affect applications, if there is a vulnerability in some library that's used by a bunch of my applications then it's expected that i will need to re-deploy updated versions of those applications, this is not difficult, i am re-deploying updated versions of my applications all the time, because that is my deployment model