I know it’s long turn support and much more stable than other versions. But I have installed MacOS and installed 2018.4.11f1 LTS and today I got a notification there is 2018.4.12f LTS available. Seems I need to install as whole new install from Hub. Why can not it gives as an update to existing LTS version without adding another release?
Installing a new version instead of overriding old files with new ones is just safer. In the past, updating the current versions was possible but the installer actually deinstalled the old version and installed the new one afterwards. At least things are clearer now. 
LTS should have kind of rolling updates. We are in an area where limited internet data access and storage. This will create many versions in Unity Hub and each patch for LTS we need to install new version and old version (so called LTS) also there. Although I agree with your point it safe than overriding.