Personally for me, it allows me to dump stuff out of my noggin good or bad. That way I can stop thinking about it and move on. A form of self reflection. I have a bad habit to hold onto thoughts and go down a rabbit hole with them in an unhealthy fashion. Basically journaling but I can store things I have learned long term.
The beauty of it is Obsidian (or really any other writing app) allows you to develop a system of writing for you. I’m not the typical writer but Obsidian allows me to write without worrying about the organization so much.
Obsidian.
Since the Internet in general is getting harder to find genuine information, it is becoming increasingly important to save anything important to you. One day it could just disappear without warning. Obsidian can be used for an offline knowledge base. Design it however you like. I do recommend NOT watching YouTube Obsidian “gurus”, their system works for them not you.
While I agree with you, hard drives do have a shelf life. How many years seems to be up for debate but it does exist. If you don’t have multiple drives that are of different ages you may be in a world of hurt one day.
Note taking multi tool: https://obsidian.md/