Every virtual or dedicated hosting server has its own Os and operates independently from the hosting servers of other clients. Updating the OS is often ignored, but doing that could have quite a lot of advantages for your sites. The most essential reason to employ the most recent version is that patches are typically released to repair security holes inside the Os code, so if you don't install the updates, you risk people with malicious intentions to take advantage of these holes and to gain access to your content. Operating system updates are also released for much better performance of the system overall and for much better compatibility with the hardware on the market, which could directly affect the performance of your sites. If the functionality and the security of your scripts is the reason to update them, you may also find out that their latest versions require an updated Os to be able to work properly, so keeping the Operating system up-to-date is always recommended.