The data model matters doesn't it?

If it's /org/orgId/blog/blogId and a user has access to only a single orgId and needs to be logged in then doing it in /blog/blogId makes sense.

But if a user has acess to multiple orgs via different orgIds, then it makes more sense to do the former with /org/orgId/blog/blogId because then the page is sharable via URL. If you do just /blog/blogId that prevents a user from easily accessing a new organization (unless you use query parameters)