Useless in the sense it doesn't really need to mention Bing. Blocking /css and /js makes sense because they don't add value in being crawled. Not necessary, bu

Useless in the sense it doesn't really need to mention Bing. Blocking /css and /js makes sense because they don't add value in being crawled. Not necessary, but doesn't hurt. Best practice: Always have a robots.txt file, even if it's empty.