> If you don't track updates in an automatic way, you are not going to even know whether you need to update something.
With dynamic linking, you may get updates for programs that need them without knowing that it was needed. If you manually build Nginx with shared libraries, and later on some fix for PCRE comes down the line and you update libpcre, your Nginx install takes advantage of that the next time it restarts. This happens whether you manually updated PCRE or a package management system does it for you. This happens for things like Chrome and Firefox too, even though they ship with quite a bit statically compiled. There are still portions they expect the system to provide (if you've even tried to get chrome working on an older system, this becomes obvious).
This is an advantage, it exists, and people make use of it all the time. You can try to argue down it's relevance, but without successfully doing so first, I think saying it's pointless is getting ahead of yourself.
> There are plenty of package management systems in current use where linking is an ideological or historical choice and has no relevance to security updates.
At the very least it would have relevance in that they would need to accurately track package dependencies and would not have the additional benefit of the package failing to install if they got it wrong. I've had plenty of times in the past where package management systems haven't even gotten that right, where everything installs but there's errors about missing libraries because of the way things are loaded on demand for some systems. There are benefits to not relying on some automated or manual tracking of this, where instead if you get it wrong it doesn't work. The fact that it requires a package management to mitigate this problem is itself a downside.
To be clear, my argument is there are both upsides and downsides to dynamic linking, and that it's not purely all negative. By arguing against that you're positioning yourself as stating that it's not a trade off, so it's all bad (or all good, but that doesn't seem to be your point). Is that really the position you intend to stand on? It seems rather absolutist.