As HAL/Col stated, you need to install the update if you have a version of Net Framework already installed.
Aside from websites, a lot of software requires the Net Framework to run.
Yes, you may not have installed it yourself. And, you most likely have just the .Net runtime installed and not the active programming environment.
One set of Microsoft updates that I do research before installing are device driver updates. More than once, Windows Update has suggested a driver that was not compatible with my hardware.
Chas