I think the greatest value in writing things down is to order and articulate your own thoughts. Certainly in my own case, I never finish a large chunk of articles I start to write simply because during the research I find out I was wrong, or that things are more complex than I thought and I'm no longer sure I'm right.
See my personal website for a post I wrote about that :-) https://arp242.net/weblog/why-write.html
An additional reason is that publishing your thoughts also means people can point out flaws or points you hadn't considered. Maintaining a website is just one way of doing that of course (commenting here is another), but I find it's a pretty effective way.