I mainly use it to record my notes and processes on photography, post processing photos and bread making. It also gets used for Linux, Ubuntu and vim tricks and tips that I find useful.
Whilst you can search Google for information, I would rather search Google once, find a good link then make my own notes that I can refer back to quicker than using Google again. I can also combine many Google links into one document as each link may have better points than the other.
Overall it’s to make my life more efficient by not having to remember everything and also “writing is learning”.