* A blog post is a snapshot: what did the author think at the time they wrote the post? If they change their mind or learn more, they write a new post and link forward and backwards. I know how to write for this environment (write what I think now, try to write things I'll feel glad to have written later) and how to work with things other people have written (consider the date, it's just one person's view).
* A wiki page is unclear. When should it be updated? How much should I trust that it was up-to-date as of the last-updated date vs that just being when someone fixed a typo? A few wikis and sites with wiki-like approaches (Wikipedia, gwern.net) manage to handle this well, but I think it's generally much more difficult and rot-prone.