I did this too - obsidian's daily note feature is fantastic, and you can extract out pages from it if you want/need to dedicate a document for a specific thing. Since it's just markdown, search is quick - and being able to use regex if I need to is awesome. The graph view, showing connections between notes is great if you create notes on specific subjects, and link them together, or pull sections out to explain more in depth - but it's not really that necessary unless you're building your own knowledgebase, which like all documentation suffers from rot over time.

As long as your note-ing tool supports a good enough search that you can find things again, then I think it doesn't really matter what you use - as you said, writing it down is the important part.